[ { "anchor": "Simultaneous phase and amplitude aberration sensing with a\n liquid-crystal vector-Zernike phase mask: We present an enhanced version of the Zernike wavefront sensor, that\nsimultaneously measures phase and amplitude aberrations. The 'vector-Zernike'\nwavefront sensor consists of a patterned liquid-crystal mask, which imposes\n$\\pm \\pi/2$ phase on the point spread function core through the achromatic\ngeometric phase acting with opposite sign on opposite circular polarizations.\nAfter splitting circular polarization, the ensuing pupil intensity images are\nused to reconstruct the phase and the amplitude of the incoming wavefront. We\ndemonstrate reconstruction of the complex wavefront with monochromatic lab\nmeasurements and show in simulation the high accuracy and sensitivity over a\nbandwidth up to $100\\%$", "positive": "In-orbit performance and calibration of the Hard X-ray Imager onboard\n Hitomi (ASTRO-H): The Hard X-ray Imager (HXI) onboard Hitomi (ASTRO-H) is an imaging\nspectrometer covering hard X-ray energies of 5-80 keV. Combined with the hard\nX-ray telescope, it enables imaging spectroscopy with an angular resolution of\n$1^\\prime.7$ half-power diameter, in a field of view of\n$9^\\prime\\times9^\\prime$. The main imager is composed of 4 layers of Si\ndetectors and 1 layer of CdTe detector, stacked to cover wide energy band up to\n80 keV, surrounded by an active shield made of BGO scintillator to reduce the\nbackground. The HXI started observations 12 days before the Hitomi loss, and\nsuccessfully obtained data from G21.5$-$0.9, Crab and blank sky. Utilizing\nthese data, we calibrate the detector response and study properties of in-orbit\nbackground. The observed Crab spectra agree well with a powerlaw model\nconvolved with the detector response, within 5% accuracy. We find that albedo\nelectrons in specified orbit strongly affect the background of Si top layer,\nand establish a screening method to reduce it. The background level over the\nfull field of view after all the processing and screening is as low as the\npre-flight requirement of $1$-$3\\times10^{-4}$ counts s$^{-1}$ cm$^{-2}$\nkeV$^{-1}$." }, { "anchor": "Maximum Likelihood Compton Polarimetry with the Compton Spectrometer and\n Imager: Astrophysical polarization measurements in the soft gamma-ray band are\nbecoming more feasible as detectors with high position and energy resolution\nare deployed. Previous work has shown that the minimum detectable polarization\n(MDP) of an ideal Compton polarimeter can be improved by $\\sim 21\\%$ when an\nunbinned, maximum likelihood method is used instead of the standard approach of\nfitting a sinusoid to a histogram of azimuthal scattering angles. Here we\noutline a procedure for implementing this maximum likelihood approach for real,\nnon-ideal polarimeters. As an example, we use the recent observation of GRB\n160530A with the Compton Spectrometer and Imager. We find that the MDP for this\nobservation is reduced by $20\\%$ when the maximum likelihood method is used\ninstead of the standard method.", "positive": "Exploration of the outer solar system with fast and small sailcraft: Two new interplanetary technologies have advanced in the past decade to the\npoint where they may enable exciting, affordable missions that reach further\nand faster deep into the outer regions of our solar system: (i) small and\ncapable interplanetary spacecraft and (ii) light-driven sails. Combination of\nthese two technologies could drastically reduce travel times within the solar\nsystem. We discuss a new paradigm that involves small and fast moving sailcraft\nthat could enable exploration of distant regions of the solar system much\nsooner and faster than previously considered. We present some of the exciting\nscience objectives for these miniaturized intelligent space systems that could\nlead to transformational advancements in the space sciences in the coming\ndecade." }, { "anchor": "A New Task: Deriving Semantic Class Targets for the Physical Sciences: We define deriving semantic class targets as a novel multi-modal task. By\ndoing so, we aim to improve classification schemes in the physical sciences\nwhich can be severely abstracted and obfuscating. We address this task for\nupcoming radio astronomy surveys and present the derived semantic radio galaxy\nmorphology class targets.", "positive": "Observations of Low-Frequency Radio Emission from Millisecond Pulsars\n and Multipath Propagation in the Interstellar Medium: Studying the gravitational-wave sky with pulsar timing arrays (PTAs) is a key\nscience goal for the Square Kilometre Array (SKA) and its pathfinder\ntelescopes. With current PTAs reaching sub-microsecond timing precision, making\naccurate measurements of interstellar propagation effects and mitigating them\neffectively has become increasingly important to realise PTA goals. As these\neffects are much stronger at longer wavelengths, low-frequency observations are\nmost appealing for characterizing the interstellar medium (ISM) along the sight\nlines toward PTA pulsars. The Murchison Widefield Array (MWA) and the\nEngineering Development Array (EDA), which utilizes MWA technologies, present\npromising opportunities for undertaking such studies, particularly for PTA\npulsars located in the southern sky. Such pulsars are also the prime targets\nfor PTA efforts planned with the South African MeerKAT, and eventually with the\nSKA. In this paper we report on observations of two bright southern millisecond\npulsars PSRs J0437-4715 and J2145-0750 made with these facilities; MWA\nobservations sampling multiple frequencies across the 80-250 MHz frequency\nrange, while the EDA providing direct-sampled baseband data to yield a large\ninstantaneous usable bandwidth of $\\sim$200 MHz. Using these observations, we\ninvestigate various aspects relating to pulsar emission and ISM properties,\nsuch as spectral evolution of the mean pulse shape, scintillation as a function\nof frequency, chromaticity in interstellar dispersion, and flux density spectra\nat low frequencies. Systematic and regular monitoring observations will help\nascertain the role of low-frequency measurements in PTA experiments, while\nsimultaneously providing a detailed characterization of the ISM toward the\npulsars, which will be useful in devising optimal observing strategies for\nfuture PTA experiments." }, { "anchor": "Progress in Monte Carlo design and optimization of the Cherenkov\n Telescope Array: The Cherenkov Telescope Array (CTA) will be an instrument covering a wide\nenergy range in very-high-energy (VHE) gamma rays. CTA will include several\ntypes of telescopes, in order to optimize the performance over the whole energy\nrange. Both large-scale Monte Carlo (MC) simulations of CTA super-sets\n(including many different possible CTA layouts as sub-sets) and smaller-scale\nsimulations dedicated to individual aspects were carried out and are on-going.\nWe summarize results of the prior round of large-scale simulations, show where\nthe design has now evolved beyond the conservative assumptions of the prior\nround and present first results from the on-going new round of MC simulations.", "positive": "3DMAP-VR, a project to visualize 3-dimensional models of astrophysical\n phenomena in virtual reality: In this research note, we present 3DMAP-VR,(3-Dimensional Modeling of\nAstrophysical Phenomena in Virtual Reality), a project aimed at visualizing 3D\nMHD models of astrophysical simulations, using virtual reality sets of\nequipment. The models account for all the relevant physical processes in\nastrophysical phenomena: gravity, magnetic-field-oriented thermal conduction,\nenergy losses due to radiation, gas viscosity, deviations from proton-electron\ntemperature equilibration, deviations from the ionization equilibrium, cosmic\nrays acceleration, etc.. We realized an excellent synergy between our 3DMAP-VR\nproject and Sketchfab (one of the largest open access platforms to publish and\nshare 3D virtual reality and augmented reality content) to promote a wide\ndissemination of results for both scientific and public outreach purposes." }, { "anchor": "Directional Dependence and Diurnal Modulation in Dark Matter Detectors: In this paper we study the effect of the channeling of ions recoiling from\ncollisions with weakly interacting massive particles (WIMPs) in single crystal\ndetectors. In particular we investigate the possibility that channeling may\ngive rise to diurnal modulations of the counting rate as the Earth rotates\nrelative to the direction of the WIMP wind, and the effect that channeling has\non the \"quenching factor\" of a detector.", "positive": "New and Extended Data Processing of Mars Odyssey Neutron Spectrometer\n Data: The Los Alamos National Laboratory designed and built Mars Odyssey Neutron\nSpectrometer (MONS) has been in excellent health operating from February 2002\nto the present. MONS measures the neutron leakage albedo from galactic cosmic\nray bombardment of Mars. These signals can indicate the presence of\nnear-surface water deposits on Mars, and can also be used to study properties\nof the seasonal polar CO$_2$ ice caps. This work outlines a new analysis of the\nMONS data that results in new and extended time-series maps of MONS thermal and\nepithermal neutron data. The new data are compared to previous publications on\nthe MONS instrument. We then present preliminary results studying the\ninter-annual variability in the polar regions of Mars based on 8 Mars-Years of\nMONS data from the new dataset." }, { "anchor": "A Novel Reflectometer for Relative Reflectance Measurements of CCDs: The high quantum efficiencies (QE) of backside illuminated charge coupled\ndevices (CCD) has ushered in the age of the large scale astronomical survey.\nThe QE of these devices can be greater than 90 %, and is dependent upon the\noperating temperature, device thickness, backside charging mechanisms, and\nanti-reflection (AR) coatings. But at optical wavelengths the QE is well\napproximated as one minus the reflectance, thus the measurement of the backside\nreflectivity of these devices provides a second independent measure of their\nQE.\n We have designed and constructed a novel instrument to measure the relative\nspecular reflectance of CCD detectors, with a significant portion of this\ndevice being constructed using a 3D fused deposition model (FDM) printer. This\ndevice implements both a monitor and measurement photodiode to simultaneously\ncollect incident and reflected measurements reducing errors introduced by the\nrelative reflectance calibration process. While most relative reflectometers\nare highly dependent upon a precisely repeatable target distance for accurate\nmeasurements, we have implemented a method of measurement which minimizes these\nerrors.\n Using the reflectometer we have measured the reflectance of two types of\nHamamatsu CCD detectors. The first device is a Hamamatsu 2k x 4k backside\nilluminated high resistivity p-type silicon detector which has been optimized\nto operate in the blue from 380 nm - 650 nm. The second detector being a 2k x\n4k backside illuminated high resistivity p-type silicon detector optimized for\nuse in the red from 640 nm - 960 nm. We have not only been able to measure the\nreflectance of these devices as a function of wavelength we have also sampled\nthe reflectance as a function of position on the device, and found a reflection\ngradient across these devices.", "positive": "ATLAS Probe: Breakthrough Science of Galaxy Evolution, Cosmology, Milky\n Way, and the Solar System: ATLAS (Astrophysics Telescope for Large Area Spectroscopy) is a concept for a\nNASA probe-class space mission. It is the spectroscopic follow-up mission to\nWFIRST, boosting its scientific return by obtaining deep NIR & MIR slit\nspectroscopy for most of the galaxies imaged by the WFIRST High Latitude Survey\nat z>0.5. ATLAS will measure accurate and precise redshifts for ~200M galaxies\nout to z=7 and beyond, and deliver spectra that enable a wide range of\ndiagnostic studies of the physical properties of galaxies over most of cosmic\nhistory. ATLAS and WFIRST together will produce a definitive 3D map of the\nUniverse over 2000 sq deg. ATLAS Science Goals are: (1) Discover how galaxies\nhave evolved in the cosmic web of dark matter from cosmic dawn through the peak\nera of galaxy assembly. (2) Discover the nature of cosmic acceleration. (3)\nProbe the Milky Way's dust-enshrouded regions, reaching the far side of our\nGalaxy. (4) Discover the bulk compositional building blocks of planetesimals\nformed in the outer Solar System. These flow down to the ATLAS Scientific\nObjectives: (1A) Trace the relation between galaxies and dark matter with less\nthan 10% shot noise on relevant scales at 1450 GHz) than those at the\nALMA site. This is due to the lower altitude of the Greenland site.\nNevertheless, half of the winter time at the Greenland site can be used for\nastronomical observations at frequencies between 450 GHz and 1000 GHz with\nopacities <1.2, and 10% of the time show >10% transmittance in the THz (1035\nGHz, 1350 GHz, and 1500 GHz) windows. One major advantage of the Greenland site\nin winter is that there is no diurnal variation due to the polar night\ncondition, and therefore the durations of low-opacity conditions are\nsignificantly longer than at the ALMA site. Opacities lower than 0.05 or 0.04\ncan continue for more than 100 hours. Such long stable opacity conditions do\nnot occur as often even at the South Pole; it happens only for the opacity\nlower than 0.05. Since the opacity variation is directly related to the sky\ntemperature (background) variation, the Greenland site is suitable for\nastronomical observations that need unusually stable sky background." }, { "anchor": "A new method for calculating the convergent point of a moving group: Context: Convergent point (CP) search methods are important tools for\nstudying the kinematic properties of open clusters and young associations whose\nmembers share the same spatial motion.\n Aims: We present a new CP search strategy based on proper motion data. We\ntest the new algorithm on synthetic data and compare it with previous versions\nof the CP search method. As an illustration and validation of the new method we\nalso present an application to the Hyades open cluster and a comparison with\nindependent results.\n Methods: The new algorithm rests on the idea of representing the stellar\nproper motions by great circles over the celestial sphere and visualizing their\nintersections as the CP of the moving group. The new strategy combines a\nmaximum-likelihood analysis for simultaneously determining the CP and selecting\nthe most likely group members and a minimization procedure that returns a\nrefined CP position and its uncertainties. The method allows one to correct for\ninternal motions within the group and takes into account that the stars in the\ngroup lie at different distances.\n Results: Based on Monte Carlo simulations, we find that the new CP search\nmethod in many cases returns a more precise solution than its previous\nversions. The new method is able to find and eliminate more field stars in the\nsample and is not biased towards distant stars. The CP solution for the Hyades\nopen cluster is in excellent agreement with previous determinations.", "positive": "Astronomy in the Church: the Clementine Sundial in Santa Maria degli\n Angeli, Rome: Pope Clement XI (1700-1721) ordered Francesco Bianchini (1662-1729) to build\na Meridian Line. Bianchini was the Secretary of the Commission for the\nCalendar. He chose the Basilica of Santa Maria degli Angeli because of the\nstability of its roman walls and foundations and its suitable dimension.\nStability over centuries of the ancient walls where the pinhole is located is a\nrequirement for making high precision astrometry, such as the measurement of\nthe inclination of the Earth axis over its orbit plan. In the 18th century it\nwas possible to open the window holding the southern pinhole, and, even in\ndaylight, stellar transits were recorded and precisely timed with pendulum\nmechanical clocks. The accuracy of such clocks was better than 1 s per day, and\nthe observations of stellar transits allowed their synchronization with\nsidereal time. This \"hybrid feature\" of the Clementine Gnomon to measure solar\nand stellar transits allowed Bianchini to accomplish in 1703 the whole\nmeasurement of the duration of the tropical year, which was usually made by\ncomparing observations very widely spread in time. The small deviation of the\nLine from true North of ~ 4'30\" Eastwards has been measured comparing the\ndelays of transits at both solstices with respect to the ephemerides." }, { "anchor": "The Cherenkov Telescope Array sensitivity to the transient sky: The Cherenkov Telescope Array (CTA) will be able to perform unprecedented\nobservations of the transient very high-energy sky. An on-line science alert\ngeneration (SAG) pipeline, with a required 30 second latency, will allow the\ndiscovery or follow-up of gamma ray bursts (GRBs) and flaring emission from\nactive galactic nuclei, galactic compact objects and electromagnetic\ncounterparts of gravitational waves or neutrino messengers. The CTA sensitivity\nfor very short exposures does not only depend on the technological performance\nof the array (e.g. effective area, background discrimination efficiency). The\nalgorithms to evaluate the significance of the detection also define the\nsensitivity, together with their computational efficiency in order to satisfy\nthe SAG latency requirements. We explore the aperture photometry and likelihood\nanalysis techniques, and the associated parameters (e.g. on-source to\noff-source exposure ratio, minimum number of required signal events), defining\nthe CTA ability to detect a significant signal at short exposures. The\nresulting CTA differential flux sensitivity as a function of the observing\ntime, obtained using the latest Monte Carlo simulations, is compared to the\nsensitivities of Fermi-LAT and current-generation IACTs obtained in the\noverlapping energy ranges.", "positive": "The Promise of Data Science for the Technosignatures Field: This paper outlines some of the possible advancements for the\ntechnosignatures searches using the new methods currently rapidly developing in\ncomputer science, such as machine learning and deep learning. It also showcases\na couple of case studies of large research programs where such methods have\nbeen already successfully implemented with notable results. We consider that\nthe availability of data from all sky, all the time observations paired with\nthe latest developments in computational capabilities and algorithms currently\nused in artificial intelligence, including automation, will spur an\nunprecedented development of the technosignatures search efforts." }, { "anchor": "The value of astrometry for exoplanet science: Exoplanets mass measurements will be a critical next step to assess the\nhabitability of Earth-like planets: a key aspect of the 2020 vision in the\nprevious decadal survey and also central to NASA's strategic priorities.\nPrecision astrometry delivers measurement of exoplanet masses, allowing\ndiscrimination of rocky planets from water worlds and enabling much better\nmodeling of their atmosphere improving species retrieval from spectroscopy. The\nscientific potential of astrometry will be enormous. The intrinsic\nastrophysical noise floor set by star spots and stellar surface activity is\nabout a factor of ten more benign for astrometry than for the more established\ntechnique of Radial Velocity, widening the discovery region and pushing\ndetection thresholds to lower masses than previously possible. On the\ninstrumental side, precision astrometry is limited by optical field distortion\nand detector calibration issues. Both technical challenges are now being\naddressed successfully in the laboratory. However, we have identified the need\nto continue these technology development efforts to achieve sub-microarcsecond\nastrometry precision necessary for detection and characterization of Earth-like\nplanets around nearby FGK stars. The international community has realized the\nimportance of astrometry, and various astrometry missions have been proposed\nand under development, with a few high profile missions now operational. We\nbelieve that it is vital for the U.S. scientific community to participate in\nthe development of these new technologies and scientific discoveries. We\nrecommend exploring alternatives to incorporate astrometric capabilities into\nfuture exoplanet flagship missions such as HABEX and LUVOIR, substantially\nincreasing the scientific return associated with the expected yield of\nearth-like planets to be recovered.", "positive": "Searching for extraterrestrial intelligence signals in astronomical\n spectra, including existing data: The main purpose of this article is to make Astronomers aware that Searches\nfor Extraterrestrial Intelligence can be carried out by analyzing standard\nastronomical spectra, including those they already have taken. Simplicity is\nthe outstanding advantage of a search in spectra. The spectra can be analyzed\nby simple eye inspection or a few lines of code that uses Fourier transform\nsoftware. Theory, confirmed by published experiments, shows that periodic\nsignals in spectra can be easily generated by sending light pulses separated by\nconstant time intervals. While part of this article, like all articles on\nsearches for ETI, is highly speculative the basic physics is sound. In\nparticular, technology now available on Earth could be used to send signals\nhaving the required energy to be detected at a target located 1000 light years\naway. Extraterrestrial Intelligence (ETI) could use these signals to make us\naware of their existence. For an ETI, the technique would also have the\nadvantage that the signals could be detected both in spectra and searches for\nintensity pulses like those currently carried out on Earth." }, { "anchor": "New Facts From the First Galaxy Distance Estimates: A new database from the NASA/IPAC Extragalactic Database (NED) of galaxy\nDistances (NED-D), normally the source for the newest precision-based\nestimates, provides access to the oldest redshift-independent extragalactic\ndistances in the publication record. Two new surprises emerge when the early\ndistance estimates are placed in chronological order. Both discoveries credited\nto Hubble based on these distances had in fact been made earlier. Hubble\nhowever, proved the case.", "positive": "Improving Performance in Java: TOPCAT and STILTS: TOPCAT and STILTS are mature Java desktop applications for working with\ntabular data that have always had a focus on efficiency for large or very large\ndata sets. This paper presents some progress, experience and lessons learned\nfrom efforts over recent years to improve performance further by multithreading\nkey algorithms as well as other strategies." }, { "anchor": "Informative regularization for a multi-layer perceptron RR Lyrae\n classifier under data shift: In recent decades, machine learning has provided valuable models and\nalgorithms for processing and extracting knowledge from time-series surveys.\nDifferent classifiers have been proposed and performed to an excellent\nstandard. Nevertheless, few papers have tackled the data shift problem in\nlabeled training sets, which occurs when there is a mismatch between the data\ndistribution in the training set and the testing set. This drawback can damage\nthe prediction performance in unseen data. Consequently, we propose a scalable\nand easily adaptable approach based on an informative regularization and an\nad-hoc training procedure to mitigate the shift problem during the training of\na multi-layer perceptron for RR Lyrae classification. We collect ranges for\ncharacteristic features to construct a symbolic representation of prior\nknowledge, which was used to model the informative regularizer component.\nSimultaneously, we design a two-step back-propagation algorithm to integrate\nthis knowledge into the neural network, whereby one step is applied in each\nepoch to minimize classification error, while another is applied to ensure\nregularization. Our algorithm defines a subset of parameters (a mask) for each\nloss function. This approach handles the forgetting effect, which stems from a\ntrade-off between these loss functions (learning from data versus learning\nexpert knowledge) during training. Experiments were conducted using recently\nproposed shifted benchmark sets for RR Lyrae stars, outperforming baseline\nmodels by up to 3\\% through a more reliable classifier. Our method provides a\nnew path to incorporate knowledge from characteristic features into artificial\nneural networks to manage the underlying data shift problem.", "positive": "KM3NeT Broadcast Optical Data Transport System: The optical data transport system of the KM3NeT neutrino telescope at the\nbottom of the Mediterranean Sea will provide each of the more than 6000 optical\nmodules in the detector arrays with a point-to-point optical connection to the\ncontrol stations onshore. The ARCA and ORCA detectors of KM3NeT are being\ninstalled at a depth of about 3500 m and 2500 m, respectively; their distance\nto the control stations is about 100 kilometers and 40 kilometers. The expected\nmaximum data rate is 200 Mbps per optical module. The implemented optical data\ntransport system matches the layouts of the networks of electro-optical cables\nand junction boxes in the deep sea. For efficient use of the fibres in the\nsystem the technology of Dense Wavelength Division Multiplexing is applied. The\nperformance of the optical system in terms of measured bit error rates, optical\nbudget and the next steps in the implementation of the system are presented." }, { "anchor": "Integration of acoustical sensors into the KM3NeT Optical Modules: The next generation multi-cubic-kilometre water Cherenkov neutrino telescope\nwill be build in the Mediterranean Sea. This telescope, called KM3NeT, is\ncurrently entering a first construction phase. The KM3NeT research\ninfrastructure will comprise 690 so-called Detection Units in its final design\nwhich will be anchored to the sea bed and held upright by submerged floats. The\npositions of these Detection Units, several hundred metres in length, and their\nattached Optical Modules for the detection of Cherenkov light have to be\nmonitored continously to provide the telescope with its desired pointing\nprecision. A standard way to do this is the utilisation of an acoustic\npositioning system using emitters at fixed positions and receivers distributed\nalong the Detection Units. The KM3NeT neutrino telescope comprises a\ncustom-made acoustic positioning system with newly designed emitters attached\nto the anchors of the Detection Units and custom-designed receivers attached to\nthe Detection Units. This article describes an approach for a receiver and its\nperformance. The proposed Opto-Acoustical Modules combine the optical sensors\nfor the telescope with the acoustical sensors necessary for the positioning of\nthe module itself. This combination leads to a compact design suited for an\neasy deployment of the numerous Detection Units. Furthermore, the instrumented\nvolume can be used for scientific analyses such as marine science and acoustic\nparticle detection.", "positive": "The Future of Time: UTC and the Leap Second: Before atomic timekeeping, clocks were set to the skies. But starting in\n1972, radio signals began broadcasting atomic seconds and leap seconds have\noccasionally been added to that stream of atomic seconds to keep the signals\nsynchronized with the actual rotation of Earth. Such adjustments were\nconsidered necessary because Earth's rotation is less regular than atomic\ntimekeeping. In January 2012, a United Nations-affiliated organization could\npermanently break this link by redefining Coordinated Universal Time. To\nunderstand the importance of this potential change, it's important to\nunderstand the history of human timekeeping." }, { "anchor": "Approximate Bayesian Neural Doppler Imaging: The non-uniform surface temperature distribution of rotating active stars is\nroutinely mapped with the Doppler Imaging technique. Inhomogeneities in the\nsurface produce features in high-resolution spectroscopic observations that\nshift in wavelength depending on their position on the visible hemisphere. The\ninversion problem has been systematically solved using maximum a-posteriori\nregularized methods assuming smoothness or maximum entropy. Our aim in this\nwork is to solve the full Bayesian inference problem, by providing access to\nthe posterior distribution of the surface temperature in the star. We use\namortized neural posterior estimation to produce a model that approximates the\nhigh-dimensional posterior distribution for spectroscopic observations of\nselected spectral ranges sampled at arbitrary rotation phases. The posterior\ndistribution is approximated with conditional normalizing flows, which are\nflexible, tractable and easy to sample approximations to arbitrary\ndistributions. When conditioned on the spectroscopic observations, they provide\na very efficient way of obtaining samples from the posterior distribution. The\nconditioning on observations is obtained through the use of Transformer\nencoders, which can deal with arbitrary wavelength sampling and rotation\nphases. Our model can produce thousands of posterior samples per second. Our\nvalidation of the model for very high signal-to-noise observations shows that\nit correctly approximates the posterior, although with some overestimation of\nthe broadening. We apply the model to the moderately fast rotator II Peg,\nproducing the first Bayesian map of its temperature inhomogenities. We conclude\nthat conditional normalizing flows are a very promising tool to carry out\napproximate Bayesian inference in more complex problems in stellar physics,\nlike constraining the magnetic properties.", "positive": "The CHIME Fast Radio Burst Project: System Overview: The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a novel transit\nradio telescope operating across the 400-800-MHz band. CHIME is comprised of\nfour 20-m x 100-m semi-cylindrical paraboloid reflectors, each of which has 256\ndual-polarization feeds suspended along its axis, giving it a >200 square\ndegree field-of-view. This, combined with wide bandwidth, high sensitivity, and\na powerful correlator makes CHIME an excellent instrument for the detection of\nFast Radio Bursts (FRBs). The CHIME Fast Radio Burst Project (CHIME/FRB) will\nsearch beam-formed, high time-and frequency-resolution data in real time for\nFRBs in the CHIME field-of-view. Here we describe the CHIME/FRB backend,\nincluding the real-time FRB search and detection software pipeline as well as\nthe planned offline analyses. We estimate a CHIME/FRB detection rate of 2-42\nFRBs/sky/day normalizing to the rate estimated at 1.4-GHz by Vander Wiel et al.\n(2016). Likely science outcomes of CHIME/FRB are also discussed. CHIME/FRB is\ncurrently operational in a commissioning phase, with science operations\nexpected to commence in the latter half of 2018." }, { "anchor": "Development of Combined Opto-Acoustical Sensor Modules: The faint fluxes of cosmic neutrinos expected at very high energies require\nlarge instrumented detector volumes. The necessary volumes in combination with\na sufficient shielding against background constitute forbidding and complex\nenvironments (e.g. the deep sea) as sites for neutrino telescopes. To withstand\nthese environments and to assure the data quality, the sensors have to be\nreliable and their operation has to be as simple as possible. A compact sensor\nmodule design including all necessary components for data acquisition and\nmodule calibration would simplify the detector mechanics and ensures the long\nterm operability of the detector. The compact design discussed here combines\noptical and acoustical sensors inside one module, therefore reducing\nelectronics and additional external instruments for calibration purposes. In\nthis design the acoustical sensor is primary used for acoustic positioning of\nthe module. The module may also be used for acoustic particle detection and\nmarine science if an appropriate acoustical sensor is chosen.\n First tests of this design are promising concerning the task of calibration.\nTo expand the field of application also towards acoustic particle detection\nfurther improvements concerning electromagnetic shielding and adaptation of the\nsingle components are necessary.", "positive": "Uncertain Photometric Redshifts with Deep Learning Methods: The need for accurate photometric redshifts estimation is a topic that has\nfundamental importance in Astronomy, due to the necessity of efficiently\nobtaining redshift information without the need of spectroscopic analysis. We\npropose a method for determining accurate multimodal photo-z probability\ndensity functions (PDFs) using Mixture Density Networks (MDN) and Deep\nConvolutional Networks (DCN). A comparison with a Random Forest (RF) is\nperformed." }, { "anchor": "Lost in space? Relativistic interstellar navigation using an astrometric\n star catalogue: The exploration of interstellar space will require autonomous navigation\nsystems that do not rely on tracking from the Earth. Here I develop a method to\ndetermine the 3D position and 3D velocity of a spacecraft in deep space using a\nstar catalogue. As a spacecraft moves away from the Sun, the observed positions\nand velocities of the stars will change relative to those in a Earth-based\ncatalogue due to parallax and aberration. By measuring just the angular\ndistances between pairs of stars, and comparing these to the catalogue, we can\ninfer the coordinates of the spacecraft via an iterative forward-modelling\nprocess. I perform simulations with existing star catalogues to demonstrate the\nmethod and to compute its performance. Using the 20 nearest stars and a modest\nangular distance measurement accuracy of 1\", the position and velocity of a\nspacecraft light years from the Sun moving at relativistic speeds can be\ndetermined to within 3 au and 2 km/s respectively. These accuracies improve\nlinearly with the measurement accuracy, e.g. with angles measured to 1 mas the\nnavigation accuracy is 1000 times better. Performance can also be improved\nusing more stars, or by including onboard measurements of the stars' radial\nvelocities, as these too are affected by the spacecraft's position and motion.", "positive": "PICARD SODISM, a space telescope to study the Sun from the middle\n ultraviolet to the near infrared: The Solar Diameter Imager and Surface Mapper (SODISM) on board the PICARD\nspace mission provides wide-field images of the photosphere and chromosphere of\nthe Sun in five narrow pass bands (centered at 215.0, 393.37, 535.7, 607.1, and\n782.2 nm). PICARD is a space mission, which was successfully launched on 15\nJune 2010 into a Sun synchronous dawn-dusk orbit. It represents a European\nasset aiming at collecting solar observations that can serve to estimate some\nof the inputs to Earth climate models. The scientific payload consists of the\nSODISM imager and of two radiometers, SOVAP (SOlar VAriability PICARD) and\nPREMOS (PREcision MOnitor Sensor), which carry out measurements that allow\nestimating the Total Solar Irradiance (TSI) and the Solar Spectral Irradiance\n(SSI) from the middle ultraviolet to the red. The SODISM telescope monitors\nsolar activity continuously. It thus produces images that can also feed SSI\nreconstruction models. Further, the objectives of SODISM encompass the probing\nof the interior of the Sun via helioseismic analysis of observations in\nintensity (on the solar disc and at the limb), and via astrometric\ninvestigations at the limb. The latter addresses especially the spectral\ndependence of the radial limb shape, and the temporal evolution of the solar\ndiameter and asphericity. After a brief review of its original science\nobjectives, this paper presents the detailed design of the SODISM instrument,\nits expected performance, and the scheme of its flight operations. Some\nobservations with SODISM are presented and discussed." }, { "anchor": "A bright impulsive solar burst detected at 30 THz: Ground- and space-based observations of solar flares from radio wavelengths\nto gamma-rays have produced considerable insights but raised several unsolved\ncontroversies. The last unexplored wavelength frontier for solar flares is in\nthe range of submillimeter and infrared wavelengths. Here we report the\ndetection of an intense impulsive burst at 30 THz using a new imaging system.\nThe 30 THz emission exhibited remarkable time coincidence with peaks observed\nat microwave, mm/submm, visible, EUV and hard X-ray wavelengths. The emission\nlocation coincides with a very weak white-light feature, and is consistent with\nheating below the temperature minimum in the atmosphere. However, there are\nproblems in attributing the heating to accelerated electrons. The peak 30 THz\nflux is several times larger than the usual microwave peak near 9 GHz,\nattributed to non-thermal electrons in the corona. The 30 THz emission could be\nconsistent with an optically thick spectrum increasing from low to high\nfrequencies. It might be part of the same spectral component found at sub-THz\nfrequencies whose nature remains mysterious. Further observations at these\nwavelengths will provide a new window for flare studies.", "positive": "A Simultaneous Dual-site Technosignature Search Using International\n LOFAR Stations: The Search for Extraterrestrial Intelligence aims to find evidence of\ntechnosignatures, which can point toward the possible existence of\ntechnologically advanced extraterrestrial life. Radio signals similar to those\nengineered on Earth may be transmitted by other civilizations, motivating\ntechnosignature searches across the entire radio spectrum. In this endeavor,\nthe low-frequency radio band has remained largely unexplored; with prior radio\nsearches primarily above 1 GHz. In this survey at 110-190 MHz, observations of\n1,631,198 targets from TESS and Gaia are reported. Observations took place\nsimultaneously with two international stations (noninterferometric) of the Low\nFrequency Array in Ireland and Sweden. We can reject the presence of any\nDoppler drifting narrowband transmissions in the barycentric frame of\nreference, with equivalent isotropic radiated power of 10 17 W, for 0.4 million\n(or 1.3 million) stellar systems at 110 (or 190) MHz. This work demonstrates\nthe effectiveness of using multisite simultaneous observations for rejecting\nanthropogenic signals in the search for technosignatures." }, { "anchor": "ExoGAN: Retrieving Exoplanetary Atmospheres Using Deep Convolutional\n Generative Adversarial Networks: Atmospheric retrievals on exoplanets usually involve computationally\nintensive Bayesian sampling methods. Large parameter spaces and increasingly\ncomplex atmospheric models create a computational bottleneck forcing a\ntrade-off between statistical sampling accuracy and model complexity. It is\nespecially true for upcoming JWST and ARIEL observations. We introduce ExoGAN,\nthe Exoplanet Generative Adversarial Network, a new deep learning algorithm\nable to recognise molecular features, atmospheric trace-gas abundances and\nplanetary parameters using unsupervised learning. Once trained, ExoGAN is\nwidely applicable to a large number of instruments and planetary types. The\nExoGAN retrievals constitute a significant speed improvement over traditional\nretrievals and can be used either as a final atmospheric analysis or provide\nprior constraints to subsequent retrieval.", "positive": "A New Residual Distribution Hydrodynamics Solver for Astrophysical\n Simulations: Many astrophysical systems can only be accurately modelled when the behaviour\nof their baryonic gas components is well understood. The residual distribution\n(RD) family of partial differential equation (PDE) solvers produce approximate\nsolutions to the corresponding fluid equations. We present a new implementation\nof the RD method. The solver efficiently calculates the evolution of the fluid,\nwith up to second order accuracy in both time and space, across an unstructured\ntriangulation, in both 2D and 3D. We implement a novel variable time stepping\nroutine, which applies a drifting mechanism to greatly improve the\ncomputational efficiency of the method. We conduct extensive testing of the new\nimplementation, demonstrating its innate ability to resolve complex fluid\nstructures, even at very low resolution. We can resolve complex structures with\nas few as 3-5 resolution elements, demonstrated by Kelvin-Helmholtz and Sedov\nblast tests. We also note that we find cold cloud destruction time scales\nconsistent with those predicted by a typical PPE solver, albeit the exact\nevolution shows small differences. The code includes three residual calculation\nmodes, the LDA, N and blended schemes, tailored for scenarios from smooth flows\n(LDA), to extreme shocks (N), and both (blended). We compare our RD solver\nresults to state-of-the-art solvers used in other astrophysical codes,\ndemonstrating the competitiveness of the new approach, particularly at low\nresolution. This is of particular interest in large scale astrophysical\nsimulations, where important structures, such as star forming gas clouds, are\noften resolved by small numbers of fluid elements." }, { "anchor": "Supporting FAIR Principles in the Astrophysics Community: the European\n Experience: FAIR principles have the intent to act as a guideline for those wishing to\nenhance the reusability of their data holdings and put specific emphasis on\nenhancing the ability of machines to automatically find and use the data, in\naddition to supporting its reuse by individuals. Interoperability, one core of\nthese principles, especially when dealing with automated systems' ability to\ninterface with each other, requires open standards to avoid restrictions that\nnegatively impact the user's experience. Open-ness of standards is best\nsupported when the governance itself is open and includes a wide range of\ncommunity participation. In this contribution we report our experience with the\nFAIR principles, interoperable systems and open governance in astrophysics. We\nreport on activities that have matured within the ESCAPE project with a focus\non interfacing the EOSC architecture and Interoperability Framework.", "positive": "A Fast Poisson Solver of Second-Order Accuracy for Isolated Systems in\n Three-Dimensional Cartesian and Cylindrical Coordinates: We present an accurate and efficient method to calculate the gravitational\npotential of an isolated system in three-dimensional Cartesian and cylindrical\ncoordinates subject to vacuum (open) boundary conditions. Our method consists\nof two parts: an interior solver and a boundary solver. The interior solver\nadopts an eigenfunction expansion method together with a tridiagonal matrix\nsolver to solve the Poisson equation subject to the zero boundary condition.\nThe boundary solver employs James's method to calculate the boundary potential\ndue to the screening charges required to keep the zero boundary condition for\nthe interior solver. A full computation of gravitational potential requires\nrunning the interior solver twice and the boundary solver once. We develop a\nmethod to compute the discrete Green's function in cylindrical coordinates,\nwhich is an integral part of the James algorithm to maintain second-order\naccuracy. We implement our method in the {\\tt Athena++} magnetohydrodynamics\ncode, and perform various tests to check that our solver is second-order\naccurate and exhibits good parallel performance." }, { "anchor": "Unsupervised Distribution Learning for Lunar Surface Anomaly Detection: In this work we show that modern data-driven machine learning techniques can\nbe successfully applied on lunar surface remote sensing data to learn, in an\nunsupervised way, sufficiently good representations of the data distribution to\nenable lunar technosignature and anomaly detection. In particular we train an\nunsupervised distribution learning neural network model to find the Apollo 15\nlanding module in a testing dataset, with no dataset specific model or\nhyperparameter tuning. Sufficiently good unsupervised data density estimation\nhas the promise of enabling myriad useful downstream tasks, including locating\nlunar resources for future space flight and colonization, finding new impact\ncraters or lunar surface reshaping, and algorithmically deciding the importance\nof unlabeled samples to send back from power- and bandwidth-constrained\nmissions. We show in this work that such unsupervised learning can be\nsuccessfully done in the lunar remote sensing and space science contexts.", "positive": "Bayesian astrostatistics: a backward look to the future: This perspective chapter briefly surveys: (1) past growth in the use of\nBayesian methods in astrophysics; (2) current misconceptions about both\nfrequentist and Bayesian statistical inference that hinder wider adoption of\nBayesian methods by astronomers; and (3) multilevel (hierarchical) Bayesian\nmodeling as a major future direction for research in Bayesian astrostatistics,\nexemplified in part by presentations at the first ISI invited session on\nastrostatistics, commemorated in this volume. It closes with an intentionally\nprovocative recommendation for astronomical survey data reporting, motivated by\nthe multilevel Bayesian perspective on modeling cosmic populations: that\nastronomers cease producing catalogs of estimated fluxes and other source\nproperties from surveys. Instead, summaries of likelihood functions (or\nmarginal likelihood functions) for source properties should be reported (not\nposterior probability density functions), including nontrivial summaries (not\nsimply upper limits) for candidate objects that do not pass traditional\ndetection thresholds." }, { "anchor": "Into the third dimension: stochastic measurements of Stokes parameters\n within the Poincar\u00e9 sphere: Inspired by recent use of polarimetry to study the Cosmic Microwave\nBackground and extragalatic supernovae, a foray into the statistical properties\nof Stokes parameters expressed in spherical coordinates is began, allowing\ncircular polarization and linear polarization to be treated in a unified\nmanner. The use of spherical coordinates is quite necessary as it permits a\nStokes polarization state to be expressed in terms of the customary\npolarization angles and degree of polarization usually needed for human\ninterpretation. As shall be demonstrated, circular and linear polarization are\nnot statistically independent quantities but intertwined in a way that is\nespecially important, for instance, at low signal-to-noise. New distributions,\nclassical estimators, and marginalizations are presented for this\n\"three-dimensional\" polarization problem including a generalization of the Rice\ndistribution. The paper concludes with discussion regarding the potential\npitfalls of a lower dimensional analysis.", "positive": "Observing Radio Pulsars in the Galactic Centre with the Square Kilometre\n Array: The discovery and timing of radio pulsars within the Galactic centre is a\nfundamental aspect of the SKA Science Case, responding to the topic of \"Strong\nField Tests of Gravity with Pulsars and Black Holes\" (Kramer et al. 2004;\nCordes et al. 2004). Pulsars have in many ways proven to be excellent tools for\ntesting the General theory of Relativity and alternative gravity theories (see\nWex (2014) for a recent review). Timing a pulsar in orbit around a companion,\nprovides a unique way of probing the relativistic dynamics and spacetime of\nsuch a system. The strictest tests of gravity, in strong field conditions, are\nexpected to come from a pulsar orbiting a black hole. In this sense, a pulsar\nin a close orbit ($P_{\\rm orb}$ < 1 yr) around our nearest supermassive black\nhole candidate, Sagittarius A* - at a distance of ~8.3 kpc in the Galactic\ncentre (Gillessen et al. 2009a) - would be the ideal tool. Given the size of\nthe orbit and the relativistic effects associated with it, even a slowly\nspinning pulsar would allow the black hole spacetime to be explored in great\ndetail (Liu et al. 2012). For example, measurement of the frame dragging caused\nby the rotation of the supermassive black hole, would allow a test of the\n\"cosmic censorship conjecture.\" The \"no-hair theorem\" can be tested by\nmeasuring the quadrupole moment of the black hole. These are two of the prime\nexamples for the fundamental studies of gravity one could do with a pulsar\naround Sagittarius A*. As will be shown here, SKA1-MID and ultimately the SKA\nwill provide the opportunity to begin to find and time the pulsars in this\nextreme environment." }, { "anchor": "Strategies for spectroscopy on Extremely Large Telescope. III -\n Remapping switched fibre systems: We explore the use of remapping techniques to improve the efficiency of\nhighly-multiplexed fibre systems for astronomical spectroscopy. This is\nparticularly important for the implementation of Diverse Field Spectroscopy\n(DFS, described in Paper II) using highly-multiplexed monolithic fibre systems\n(MFS). Diverse Field Spectroscopy allows arbitrary distributions of target\nregions to be addressed to optimise observing efficiency when observing\ncomplex, clumpy structures such as protoclusters which will be increasingly\naccessible to Extremely Large Telescopes (ELTS). We show how the adoption of\nvarious types of remapping between the input and output of a Monolithic Fibre\nSystems can allow contiguous regions of spatial elements to be selected using\nonly simple switch arrays. Finally we show how this compares in efficiency with\nintegral-field and multiobject spectroscopy by simulations using artificial and\nreal catalogues of objects. With the adoption of these mapping strategies, DFS\noutperforms other techniques when addressing a range of realistic target\ndistributions. These techniques are also applicable to bio-medical science and\nwere in fact inspired by it.", "positive": "Astrometrically Registered Simultaneous Observations of the 22 GHz\n H$_2$O and the 43GHz SiO masers towards R Leonis Minoris using KVN and\n Source/Frequency Phase Referencing: Oxygen-rich Asymptotic Giant Branch (AGB) stars can be intense emitters of\nSiO ($v$=1 and 2, J=1$\\rightarrow$0) and H$_2$O maser lines at 43 and 22 GHz,\nrespectively. VLBI observations of the maser emission provide a unique tool to\nprobe the innermost layers of the circumstellar envelopes in AGB stars.\nNevertheless, the difficulties in achieving astrometrically aligned \\water\\ and\n$v$=1 and $v$=2 SiO maser maps have traditionally limited the physical\nconstraints that can be placed on the SiO maser pumping mechanism. We present\nphase referenced simultaneous spectral-line VLBI images for the SiO $v$=1 and\n$v$=2, J=1$\\rightarrow$0, and H$_2$O maser emission around the AGB star R\\,LMi,\nobtained from the Korean VLBI Network (KVN). The simultaneous multi-channel\nreceivers of the KVN offer great possibilities for astrometry in the frequency\ndomain. With this facility we have produced images with bona-fide absolute\nastrometric registration between high frequency maser transitions of different\nspecies to provide the positions of the \\water\\ maser emission, and the centre\nof the SiO maser emission, and hence reducing the uncertainty in the proper\nmotion for R\\,LMi by an order of magnitude over that from Hipparcos. This is\nthe first successful demonstration of source frequency phase referencing for\nmm-VLBI spectral-line observations and also where the ratio between the\nfrequencies is not an integer." }, { "anchor": "Application of an Upwind Integration Method to Plane Parallel Hall-MHD: We study the impact of an Upwind scheme on the numerical convergence of\nsimulations of the Hall and Ohmic effect in neutron stars crusts. While\nsimulations of these effects have explored a variety of geometries and wide\nranges of physical parameters, they are limited to relatively low values of the\nHall parameter, playing the role of the magnetic Reynolds number, which should\nbe not exceed a few hundred for numerical convergence.\n We study the evolution of the magnetic field in a plane-parallel Cartesian\ngeometry. We discretise the induction equation using a finite difference scheme\nand then integrate it via the Euler forward method. Two different approaches\nare used for the integration of the advective terms appearing in the equation:\na Forward Time and Central in Space (FTCS) and an Upwind scheme. We compare\nthem in terms of accuracy and performance. We explore the impact of the Upwind\nmethod on convergence according to the ratio of planar to vertical field and\nthe Hall parameter. In the limit of a low strength planar field the use of an\nUpwind scheme provides a vast improvement leading to the convergence of\nsimulations where the Hall parameter is 2 orders of magnitude higher than that\nof the FTCS. Upwind is still better if the planar field is stronger, yet, the\ndifference of the maximum value of the Hall parameter reached is within a\nfactor of 10 or a few. Moreover, we notice if the schemes diverge their\nbehaviour is very different, with FTCS producing infinite energy, while the\nUpwind scheme only temporarily increasing the overall magnetic field energy.\n Overall, the Upwind scheme enhances the efficiency of the simulations\nallowing the exploration of environments with higher value of electric\nconductivity getting us closer than before to realistic environmental\nconditions of magnetars.", "positive": "Freeform three-mirror anastigmatic large-aperture telescope and receiver\n optics for CMB-S4: CMB-S4, the next-generation ground-based cosmic microwave background (CMB)\nobservatory, will provide detailed maps of the CMB at millimeter wavelengths to\ndramatically advance our understanding of the origin and evolution of the\nuniverse. CMB-S4 will deploy large and small aperture telescopes with hundreds\nof thousands of detectors to observe the CMB at arcminute and degree\nresolutions at millimeter wavelengths. Inflationary science benefits from a\ndeep delensing survey at arcminute resolutions capable of observing a large\nfield of view at millimeter wavelengths. This kind of survey acts as a\ncomplement to a degree angular resolution survey. The delensing survey requires\na nearly uniform distribution of cameras per frequency band across the focal\nplane. We present a large-throughput, large-aperture (5-meter diameter)\nfreeform three-mirror anastigmatic telescope and an array of 85 cameras for CMB\nobservations at arcminute resolutions, which meets the needs of the delensing\nsurvey of CMB-S4. A detailed prescription of this three-mirror telescope and\ncameras is provided, with a series of numerical calculations that indicate\nexpected optical performance and mechanical tolerance." }, { "anchor": "Modeling Charge Cloud Dynamics in Cross Strip Semiconductor Detectors: When a $\\gamma$-ray interacts in a semiconductor detector, the resulting\nelectron-hole charge clouds drift towards their respective electrodes for\nsignal collection. These charge clouds will expand over time due to both\nthermal diffusion and mutual electrostatic repulsion. Solutions to the\nresulting charge profiles are well understood for the limiting cases accounting\nfor only diffusion and only repulsion, but the general solution including both\neffects can only be solved numerically. Previous attempts to model these\neffects have taken into account the broadening of the charge profile due to\nboth effects, but have simplified the shape of the profile by assuming Gaussian\ndistributions. However, the detailed charge profile can have important impacts\non charge sharing in multi-electrode strip detectors. In this work, we derive\nan analytical approximation to the general solution, including both diffusion\nand repulsion, that closely replicates both the width and the detailed shape of\nthe charge profiles. This analytical solution simplifies the modeling of charge\nclouds in semiconductor strip detectors.", "positive": "The probability distribution functions of emission line flux\n measurements and their ratios: Many physical parameters in astrophysics are derived using the ratios of two\nobserved quantities. If the relative uncertainties on measurements are small\nenough, uncertainties can be propagated analytically using simplifying\nassumptions, but for large normally distributed uncertainties, the probability\ndistribution of the ratio become skewed, with a modal value offset from that\nexpected in Gaussian uncertainty propagation. Furthermore, the most likely\nvalue of a ratio A/B is not equal to the reciprocal of the most likely value of\nB/A. The effect is most pronounced when the uncertainty on the denominator is\nlarger than that on the numerator.\n We show that this effect is seen in an analysis of 12,126 spectra from the\nSloan Digital Sky Survey. The intrinsically fixed ratio of the [O III] lines at\n4959 and 5007 ${\\AA}$ is conventionally expressed as the ratio of the stronger\nline to the weaker line. Thus, the uncertainty on the denominator is larger,\nand non-Gaussian probability distributions result. By taking this effect into\naccount, we derive an improved estimate of the intrinsic 5007/4959 ratio. We\nobtain a value of 3.012 $\\pm$ 0.008, which is slightly but statistically\nsignificantly higher than the theoretical value of 2.98.\n We further investigate the suggestion that fluxes measured from emission\nlines at low signal to noise are strongly biased upwards. We were unable to\ndetect this effect in the SDSS line flux measurements, and we could not\nreproduce the results of Rola and Pelat who first described this bias. We\nsuggest that the magnitude of this effect may depend strongly on the specific\nfitting algorithm used." }, { "anchor": "The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) Survey\n Design, Reductions, and Detections: We describe the survey design, calibration, commissioning, and emission-line\ndetection algorithms for the Hobby-Eberly Telescope Dark Energy Experiment\n(HETDEX). The goal of HETDEX is to measure the redshifts of over a million\nLy$\\alpha$ emitting galaxies between 1.88 10 which are sufficiently bright for detailed\nfollow-up spectroscopy. Crucially, we propose a wide-field spectroscopic\nnear-IR + mid-IR capability which will greatly enhance our understanding of the\nfirst galaxies by detecting and identifying a statistical sample of the first\ngalaxies and the first SMBH, and to chart the metal enrichment history of\ngalaxies in the early Universe - potentially finding signatures of the very\nfirst stars to form from metal-free primordial gas. The wide-field and\nwavelength range of SPACE will also provide us a unique opportunity to study\nstar formation by performing a wide survey of the Milky Way in the near-IR +\nmid-IR. This science project can be enabled either by a stand-alone ESA-led M\nmission or by an instrument for an L mission (with ESA and/or NASA, JAXA and\nother international space agencies) with a wide-field (sub-)millimetre\ncapability at wavelength > 500 microns." }, { "anchor": "Monitoring activities of satellite data processing services in real-time\n with SDDS Live Monitor: This work describes Live Monitor, the monitoring subsystem of SDDS - an\nautomated system for space experiment data processing, storage, and\ndistribution created at SINP MSU. Live Monitor allows operators and developers\nof satellite data centers to identify errors occurred in data processing\nquickly and to prevent further consequences caused by the errors. All\nactivities of the whole data processing cycle are illustrated via a web\ninterface in real-time. Notification messages are delivered to responsible\npeople via emails and Telegram messenger service. The flexible monitoring\nmechanism implemented in Live Monitor allows us to dynamically change and\ncontrol events being shown on the web interface on our demands. Physicists,\nwhose space weather analysis models are functioning upon satellite data\nprovided by SDDS, can use the developed RESTful API to monitor their own events\nand deliver customized notification messages by their needs.", "positive": "Search for Exotic Physics with the ANTARES Detector: Besides the detection of high energy neutrinos, the ANTARES telescope offers\nan opportunity to improve sensitivity to exotic cosmological relics. In this\narticle we discuss the sensitivity of the ANTARES detector to elativistic\nmonopoles and slow nuclearites. Dedicated trigger algorithms and search\nstrategies are being developed to search or them. The data filtering,\nbackground rejection selection criteria are described, as well as the expected\nsensitivity of ANTARES to exotic physics." }, { "anchor": "Fundamental limit of single-mode integral-field spectroscopy: There are several high-performance adaptive optics systems that deliver\ndiffraction-limited imaging on ground-based telescopes, which renewed the\ninterest of single-mode fiber (SMF) spectroscopy for exoplanet\ncharacterization. However, the fundamental mode of a telescope is not well\nmatched to those of conventional SMFs. With the recent progress in asphere\nmanufacturing techniques it may be possible to reshape the fundamental mode of\na SMF into any arbitrary distribution. An optimization problem is setup to\ninvestigate what the optimal mode field distribution is and what the\nfundamental throughput limit is for SMF spectroscopy. Both single-object\nspectrographs and integral-field spectrographs are investigated. The optimal\nmode for single-object spectrographs is found to be the aperture function of\nthe exit pupil, while for integral-field spectrographs the optimal mode depends\non the spatial sampling of the focal plane. For dense sampling, a uniform mode\nis optimal, while for sparse sampling, the mode of a conventional SMF is near\noptimal. With the optimal fiber mode, high throughput (>80%) can be achieved\nwhen the focal plane is (super) Nyquist sampled. For the Nyquist sampled cases,\nthe optimal mode has almost 20% more throughput than a conventional SMF.", "positive": "Triboelectric Backgrounds to radio-based UHE Neutrino Exeperiments: The proposed IceCube-Gen2 (ICG2) seeks to instrument ~500 sq. km of Antarctic\nice near the geographic South Pole with radio antennas, in order to observe the\nhighest energy (E>1 EeV) neutrinos in the Universe. To this end, ICG2 will use\nthe impulsive radio-frequency (RF) signal produced by neutrino interactions in\npolar ice caps. In such experiments, rare single event candidates must be\nunambiguously separated from background; to date, signal identification\nstrategies primarily reject thermal noise and anthropogenic backgrounds. Here,\nwe consider the possibility that fake neutrino signals may also be naturally\ngenerated via the 'triboelectric effect'. This broadly includes any process in\nwhich force applied at a boundary layer results in displacement of surface\ncharge, generating a potential difference {\\Delta}V. Wind blowing over granular\nsurfaces such as snow can induce such a {\\Delta}V, with subsequent discharge.\nDischarges over nanosecond-timescales can then lead to RF emissions at\ncharacteristic MHz-GHz frequencies. We find that such backgrounds are evident\nin the several neutrino experiments considered, and are generally characterized\nby: a) a threshold wind velocity which likely depends on the experimental\nsignal trigger threshold and layout; for the experiments considered herein,\nthis value is typically O(10 m/s), b) frequency spectra generally shifted to\nthe low-end of the frequency regime to which current radio experiments are\ntypically sensitive (100-200 MHz), c) for the strongest background signals, an\napparent preference for discharges from above-surface structures, although the\npresence of more isotropic, lower amplitude triboelectric discharges cannot be\nexcluded." }, { "anchor": "Simultaneous High Dynamic Range Algorithm, Testing, and Instrument\n Simulation: Within an imaging instrument's field of view, there may be many observational\ntargets of interest. Similarly, within a spectrograph's bandpass, there may be\nmany emission lines of interest. The brightness of these targets and lines can\nbe orders of magnitude different, which poses a challenge to instrument and\nmission design. A single exposure can saturate the bright emission and/or have\na low signal to noise ratio (SNR) for faint emission. Traditional high dynamic\nrange (HDR) techniques solve this problem by either combining multiple\nsequential exposures of varied duration or splitting the light to different\nsensors. These methods, however, can result in the loss of science capability,\nreduced observational efficiency, or increased complexity and cost. The\nsimultaneous HDR method described in this paper avoids these issues by\nutilizing a special type of detector whose rows can be read independently to\ndefine zones that are then composited, resulting in areas with short or long\nexposure measured simultaneously. We demonstrate this technique for the sun,\nwhich is bright on disk and faint off disk. We emulated these conditions in the\nlab to validate the method. We built an instrument simulator to demonstrate the\nmethod for a realistic solar imager and input. We then calculated SNRs, finding\na value of 45 for a faint coronal mass ejection (CME) and 200 for a bright CME,\nboth at 3.5 $R_{\\odot}$ -- meeting or far exceeding the international standard\nfor digital photography that defines a SNR of 10 as acceptable and 40 as\nexcellent. Future missions should consider this type of hardware and technique\nin their trade studies for instrument design.", "positive": "Online classification for time-domain astronomy: The advent of synoptic sky surveys has spurred the development of techniques\nfor real-time classification of astronomical sources in order to ensure timely\nfollow-up with appropriate instruments. Previous work has focused on algorithm\nselection or improved light curve representations, and naively convert light\ncurves into structured feature sets without regard for the time span or phase\nof the light curves. In this paper, we highlight the violation of a fundamental\nmachine learning assumption that occurs when archival light curves with long\nobservational time spans are used to train classifiers that are applied to\nlight curves with fewer observations. We propose two solutions to deal with the\nmismatch in the time spans of training and test light curves. The first is the\nuse of classifier committees where each classifier is trained on light curves\nof different observational time spans. Only the committee member whose training\nset matches the test light curve time span is invoked for classification. The\nsecond solution uses hierarchical classifiers that are able to predict source\ntypes both individually and by sub-group, so that the user can trade-off an\nearlier, more robust classification with classification granularity. We test\nboth methods using light curves from the MACHO survey, and demonstrate their\nusefulness in improving performance over similar methods that naively train on\nall available archival data." }, { "anchor": "High-contrast imaging in polychromatic light with the self-coherent\n camera: Context. In the context of direct imaging of exoplanets, coronagraphs are\ncommonly proposed to reach the required very high contrast levels. However,\nwavefront aberrations induce speckles in their focal plane and limit their\nperformance. Aims. An active correction of these wavefront aberrations using a\ndeformable mirror upstream of the coronagraph is mandatory. These aberrations\nneed to be calibrated and focal-plane wavefront-sensing techniques in the\nscience channel are being developed. One of these, the self-coherent camera, of\nwhich we present the latest laboratory results. Methods. We present here an\nenhancement of the method: we directly minimized the complex amplitude of the\nspeckle field in the focal plane. Laboratory tests using a four-quadrant\nphase-mask coronagraph and a 32x32 actuator deformable mirror were conducted in\nmonochromatic light and in polychromatic light for different bandwidths.\nResults. We obtain contrast levels in the focal plane in monochromatic light\nbetter than 3.10^-8 (RMS) in the 5 - 12 {\\lambda}/D region for a correction of\nboth phase and amplitude aberrations. In narrow bands (10 nm) the contrast\nlevel is 4.10^-8 (RMS) in the same region. Conclusions. The contrast level is\ncurrently limited by the amplitude aberrations on the bench. We identified\nseveral improvements that can be implemented to enhance the performance of our\noptical bench in monochromatic as well as in polychromatic light.", "positive": "Stacking for Cosmic Magnetism with SKA Surveys: Stacking polarized radio emission in SKA surveys provides statistical\ninformation on large samples that is not accessible otherwise due to\nlimitations in sensitivity, source statistics in small fields, and averaging\nover frequency (including Faraday synthesis). Polarization is a special case\nbecause one obvious source of stacking targets is the Stokes I source catalog,\npossibly in combination with external catalogs, for example an SKA HI survey or\na non-radio survey. We point out the significance of stacking sub-samples\nselected by additional observable parameters to investigate relations that\nreveal more about the physics of the source. Applications of stacking\npolarization include, but are not limited to, obtaining in a statistical sense\npolarization information to the detection limit in total intensity,\ndepolarization as a function of cosmic time at consistent source-frame\nwavelengths, magnetic field properties in objects with a low radio luminosity\nsuch as dwarf and low-surface-brightness galaxies, and investigating potential\ncorrelations of observable parameters with the average magnetic field direction\nin a sample. We also point out the potential use of stacking in validating the\npolarization calibration of a survey. While stacking is flexible in terms of\nsurvey definition, we discuss optimal survey parameters for the science\nexperiments presented, as well as computing and archiving requirements." }, { "anchor": "Report on Mega-Constellations to the Government of Canada and the\n Canadian Space Agency: This document provides recommendations to the Government of Canada and the\nCanadian Space Agency in response to their call for feedback on the future of\nCanadian space exploration. The report focuses on how the construction and\nlong-term placement of mega-constellations of satellites into Earth orbit will\naffect astronomy and the view of the night sky by all peoples, with attention\nto all Canadians. The broader discussion highlights several environmental\nconcerns associated with the construction and maintenance of these\nmega-constellations. The eight recommendations here address ways that Canada\ncan play a role in mitigating some of these negative effects through national\nand international initiatives. In drafting the recommendations, we take the\napproach that space needs to be developed sustainably. In this regard, we use\nthe Brundtland Report's definition: \"Sustainable development is the development\nthat meets the needs of the present without compromising the ability of future\ngenerations to meet their own needs.\" Thus, all recommendations here are made\nwith the intent of minimizing the negative consequences of mega-constellations,\nwhile also recognizing that their development will continue.", "positive": "The effect of hardware-computed travel-time on localization accuracy in\n the inversion of experimental (acoustic) waveform data: This study aims to advance hardware-level computations for travel-time\ntomography applications in which the wavelength is close to the diameter of the\ninformation that has to be recovered. Such can be the case, for example, in the\nimaging applications of (1) biomedical physics, (2) astro-geophysics and (3)\ncivil engineering. Our aim is to shed light on the effect of that preprocessing\nthe digital waveform signal has on the inversion results and to find\ncomputational solutions that guarantee robust inversion when there are\nincomplete and/or noisy measurements. We describe a hardware-level\nimplementation for integrated and thresholded travel-time computation (ITT and\nTTT). We compare the ITT and TTT approaches in inversion analysis with\nexperimental acoustic travel-time data recorded using a ring geometry for the\ntransmission and measurement points. The results obtained suggest that ITT is\nessential for maintaining the robustness of the inversion with imperfect signal\ndigitization and sparsity. In order to ensure the relevance of the results, the\nspecifications of the test setup were related to those of applications (1)-(3)." }, { "anchor": "Atmospheric muon suppression for Baikal-GVD cascade analysis: Baikal-GVD (Gigaton Volume Detector) is a neutrino telescope installed at a\ndepth of 1366 m in Lake Baikal. The expedition of 2023 brought the number of\noptical modules in the array up to 3492 (including experimental strings). These\noptical modules detect the Cherenkov radiation from secondary charged particles\ncoming from the neutrino interactions. Neutrinos produce different kinds of\ntopologically distinct light signatures. Charged current muon neutrino\ninteractions create an elongated track in the water. Charged and neutral\ncurrent interactions of other neutrino flavors yield hadronic and\nelectromagnetic cascades. The background in the neutrino cascade channel arises\nmainly due to discrete stochastic energy losses produced along atmospheric muon\ntracks. In this paper, a developed algorithm for the cascade event selection is\npresented.", "positive": "The Infra-Red Telescope (IRT) on board the THESEUS mission: The Infra-Red Telescope (IRT) is part of the payload of the THESEUS mission,\nwhich is one of the two ESA M5 candidates within the Cosmic Vision program,\nplanned for launch in 2032. The THESEUS payload, composed by two high energy\nwide field monitors (SXI and XGIS) and a near infra-red telescope (IRT), is\noptimized to detect, localize and characterize Gamma-Ray Bursts and other\nhigh-energy transients. The main goal of the IRT is to identify and precisely\nlocalize the NIR counterparts of the high-energy sources and to measure their\ndistance. Here we present the design of the IRT and its expected performance." }, { "anchor": "Calibration requirements for Epoch of Reionization 21-cm signal\n observations -- II. Analytical estimation of the bias and variance with\n time-correlated residual gains: Observation of redshifted 21-cm signals from neutral hydrogen holds the key\nto understanding the structure formation and its evolution during the\nreionization and post-reionization era. Apart from the presence of orders of\nmagnitude larger foregrounds in the observed frequency range, the instrumental\neffects of the interferometers combined with the ionospheric effects present a\nconsiderable challenge in the extraction of 21-cm signals from strong\nforegrounds. The systematic effects of time and frequency correlated residual\ngain errors originating from the measurement process introduce a bias and\nenhance the variance of the power spectrum measurements. In this work, we study\nthe effect of time-correlated residual gain errors in the presence of strong\nforeground. We present a method to produce analytic estimates of the bias and\nvari ance in the power spectrum. We use simulated observations to confirm the\nefficacy of this method and then use it to understand various effects of the\ngain errors. We find that as the standard deviation in the residual gain errors\nincreases, the bias in the estimation supersedes the variance. It is observed\nthat an optimal choice of the time over which the gain solutions are estimated\nminimizes the risk. We also find that the interferometers with higher baseline\ndensities are preferred instruments for these studies.", "positive": "MinXSS-2 CubeSat mission overview: Improvements from the successful\n MinXSS-1 mission: The second Miniature X-ray Solar Spectrometer (MinXSS-2) CubeSat, which\nbegins its flight in late 2018, builds on the success of MinXSS-1, which flew\nfrom 2016-05-16 to 2017-05-06. The science instrument is more advanced -- now\ncapable of greater dynamic range with higher energy resolution. More data will\nbe captured on the ground than was possible with MinXSS-1 thanks to a\nsun-synchronous, polar orbit and technical improvements to both the spacecraft\nand the ground network. Additionally, a new open-source beacon decoder for\namateur radio operators is available that can automatically forward any\ncaptured MinXSS data to the operations and science team. While MinXSS-1 was\nonly able to downlink about 1 MB of data per day corresponding to a data\ncapture rate of about 1%, MinXSS-2 will increase that by at least a factor of\n6. This increase of data capture rate in combination with the mission's longer\norbital lifetime will be used to address new science questions focused on how\ncoronal soft X-rays vary over solar cycle timescales and what impact those\nvariations have on the earth's upper atmosphere." }, { "anchor": "Design and Performance Analysis of a Highly Efficient Polychromatic\n Full-Stokes Polarization Modulator for the CRISP Imaging Spectrometer: We present the design and performance of a polychromatic polarization\nmodulator for the CRisp Imaging SpectroPolarimeter (CRISP) Fabry-Perot tunable\nnarrow-band imaging spectropolarimer at the Swedish 1-m Solar Telescope (SST).\nWe discuss the design process in depth, compare two possible modulator designs\nthrough a tolerance analysis, and investigate thermal sensitivity of the\nselected design. The trade-offs and procedures described in this paper are\ngenerally applicable in the development of broadband polarization modulators.\nThe modulator was built and has been operational since 2015. Its measured\nperformance is close to optimal between 500 and 900~nm, and differences between\nthe design and as-built modulator are largely understood. We show some example\ndata, and briefly review scientific work that used data from SST/CRISP and this\nmodulator.", "positive": "NDRIO White Paper: Envisioning Digital Research Infrastructure for the\n Simons Observatory: Observations of the cosmic microwave background (CMB) are an incredibly\nfertile source of information for studying the origins and evolution of the\nUniverse. Canadian digital research infrastructure (DRI) has played a key role\nin reducing ever-larger quantities of raw data into maps of the CMB suitable\nfor scientific analysis, as exemplified by the many scientific results produced\nby the Atacama Cosmology Telescope (ACT) over the past decade. The Simons\nObservatory (SO), due to start observing in 2023, will be able to measure the\nCMB with about an order of magnitude more sensitivity than ACT and other\ncurrent telescopes. In this White Paper we outline how Canadian DRI under the\nNew Digital Research Infrastructure Organization (NDRIO) could build upon the\nlegacy of ACT and play a pivotal role in processing SO data, helping to produce\ndata products that will be central to the cosmology community for years to\ncome. We include estimates of DRI resources required for this work to indicate\nwhat kind of advanced research computing (ARC) would best support an SO-like\nproject. Finally, we comment on how ARC allocations could be structured for\nlarge collaborations like SO and propose a research data management (RDM)\nsystem that makes public data releases available not only for download but also\nfor direct analysis on Canadian DRI." }, { "anchor": "Connecting the time domain community with the Virtual Astronomical\n Observatory: The time domain has been identified as one of the most important areas of\nastronomical research for the next decade. The Virtual Observatory is in the\nvanguard with dedicated tools and services that enable and facilitate the\ndiscovery, dissemination and analysis of time domain data. These range in scope\nfrom rapid notifications of time-critical astronomical transients to annotating\nlong-term variables with the latest modeling results. In this paper, we will\nreview the prior art in these areas and focus on the capabilities that the VAO\nis bringing to bear in support of time domain science. In particular, we will\nfocus on the issues involved with the heterogeneous collections of (ancillary)\ndata associated with astronomical transients, and the time series\ncharacterization and classification tools required by the next generation of\nsky surveys, such as LSST and SKA.", "positive": "Characterising the Atmospheres of Transiting Planets with a Dedicated\n Space Telescope: Exoplanetary science is among the fastest evolving fields of today's\nastronomical research. Ground-based planet-hunting surveys alongside dedicated\nspace missions (Kepler, CoRoT) are delivering an ever-increasing number of\nexoplanets, now numbering at ~690, with ESA's GAIA mission planned to bring\nthis number into the thousands. The next logical step is the characterisation\nof these worlds: what is their nature? Why are they as they are? The use of the\nHST and Spitzer Space Telescope to probe the atmospheres of transiting hot,\ngaseous exoplanets has demonstrated that it is possible with current technology\nto address this ambitious goal. The measurements have also shown the difficulty\nof understanding the physics and chemistry of these environments when having to\nrely on a limited number of observations performed on a handful of objects. To\nprogress substantially in this field, a dedicated facility for exoplanet\ncharacterization with an optimised instrument design (detector performance,\nphotometric stability, etc.), able to observe through time and over a broad\nspectral range a statistically significant number of planets, will be\nessential. We analyse the performances of a 1.2/1.4m space telescope for\nexoplanet transit spectroscopy from the visible to the mid IR, and present the\nSNR ratio as function of integration time and stellar magnitude/spectral type\nfor the acquisition of spectra of planetary atmospheres in a variety of\nscenarios: hot, warm, and temperate planets, orbiting stars ranging in spectral\ntype from hot F to cool M dwarfs. We include key examples of known planets\n(e.g. HD 189733b, Cancri 55 e) and simulations of plausible terrestrial and\ngaseous planets, with a variety of thermodynamical conditions. We conclude that\neven most challenging targets, such as super-Earths in the habitable-zone of\nlate-type stars, are within reach of a M-class, space-based spectroscopy\nmission." }, { "anchor": "The H.E.S.S. Gravitational Wave Rapid Follow-up Program during O2 and O3: Since 2015, the direct detection of Gravitational Waves (GWs) became possible\nwith ground-based interferometers like LIGO and Virgo. GWs became the center of\nattention of the astronomical community and electromagnetic observatories took\na particular interest in follow-up observations of such events. The main\nsetback of these observations is the poor localization of GW events. In fact,\nGW localization uncertainties can span tens to hundreds of deg$^{2}$ the sky\neven with the advanced configurations of current GW interferometers. In this\ncontribution, we present five follow-up strategies developed for the High\nEnergy Stereoscopic System (H.E.S.S.) and assess their performances. We show\nhow a 2D and 3D galaxy targeted search approach exploiting the integral\nprobability inside the instruments field of view are best suited for medium\nfield of view instruments like H.E.S.S. We also develop an automatic response\nscheme within the H.E.S.S. Transient Follow-up system that is optimized for\nfast response and is capable of responding promptly to all kind of GW alerts.\nGW events are filtered by the developed scheme and prompt and afterglow\nobservations are automatically scheduled. The H.E.S.S. response latency to\nprompt alerts is measured to be less than 1 minute. With this continually\noptimized GW response scheme, H.E.S.S. scheduled several GW follow-up\nobservations during the second and third LIGO/Virgo observation runs.", "positive": "Cosmology Large Angular Scale Surveyor (CLASS) Focal Plane Development: The Cosmology Large Angular Scale Surveyor (CLASS) will measure the\npolarization of the Cosmic Microwave Background to search for and characterize\nthe polarized signature of inflation. CLASS will operate from the Atacama\nDesert and observe $\\sim$70% of the sky. A variable-delay polarization\nmodulator (VPM) modulates the polarization at $\\sim$10 Hz to suppress the 1/f\nnoise of the atmosphere and enable the measurement of the large angular scale\npolarization modes. The measurement of the inflationary signal across angular\nscales that span both the recombination and reionization features allows a test\nof the predicted shape of the polarized angular power spectra in addition to a\nmeasurement of the energy scale of inflation.\n CLASS is an array of telescopes covering frequencies of 38, 93, 148, and 217\nGHz. These frequencies straddle the foreground minimum and thus allow the\nextraction of foregrounds from the primordial signal. Each focal plane contains\nfeedhorn-coupled transition-edge sensors that simultaneously detect two\northogonal linear polarizations. The use of single-crystal silicon as the\ndielectric for the on-chip transmission lines enables both high efficiency and\nuniformity in fabrication. Integrated band definition has been implemented that\nboth controls the bandpass of the single mode transmission on the chip and\nprevents stray light from coupling to the detectors." }, { "anchor": "Improving Multi-Dimensional Data Formats, Access, and Assimilation Tools\n for the Twenty-First Century: Heliophysics image data largely relies on a forty-year-old ecosystem built on\nthe venerable Flexible Image Transport System (FITS) data standard. While many\nin situ measurements use newer standards, they are difficult to integrate with\nmultiple data streams required to develop global understanding. Additionally,\nmost data users still engage with data in much the same way as they did decades\nago. However, contemporary missions and models require much more complex\nsupport for 3D multi-parameter data, robust data assimilation strategies, and\nintegration of multiple individual data streams required to derive complete\nphysical characterizations of the Sun and Heliospheric plasma environment. In\nthis white paper we highlight some of the 21$^\\mathsf{st}$ century challenges\nfor data frameworks in heliophysics, consider an illustrative case study, and\nmake recommendations for important steps the field can take to modernize its\ndata products and data usage models. Our specific recommendations include: (1)\nInvesting in data assimilation capability to drive advanced data-constrained\nmodels, (2) Investing in new strategies for integrating data across multiple\ninstruments to realize measurements that cannot be produced from single\nobservations, (3) Rethinking old data use paradigms to improve user access,\ndevelop deep understanding, and decrease barrier to entry for new datasets, and\n(4) Investing in research on data formats better suited for multi-dimensional\ndata and cloud-based computing.", "positive": "Hybrid Physical-Deep Learning Model for Astronomical Inverse Problems: We present a Bayesian machine learning architecture that combines a\nphysically motivated parametrization and an analytic error model for the\nlikelihood with a deep generative model providing a powerful data-driven prior\nfor complex signals. This combination yields an interpretable and\ndifferentiable generative model, allows the incorporation of prior knowledge,\nand can be utilized for observations with different data quality without having\nto retrain the deep network. We demonstrate our approach with an example of\nastronomical source separation in current imaging data, yielding a physical and\ninterpretable model of astronomical scenes." }, { "anchor": "Per aspera ad astra simul: Through difficulties to the stars together: In this article, we detail the strategic partnerships \"Per Aspera Ad Astra\nSimul\" and \"European Collaborating Astronomers Project:\nEspa\\~na-Czechia-Slovakia\". These strategic partnerships were conceived to\nfoment international collaboration for educational activities (aimed at all\nlevels) as well as to support the development and growth of early career\nresearchers. The activities, carried out under the auspices of these strategic\npartnerships, demonstrate that Key Action 2 of the Erasmus+ programme can be an\nextremely valuable resource for supporting international educational projects,\nas well as the great impact that such projects can have on the general public\nand on the continued development of early career researchers. We strongly\nencourage other educators to make use of the opportunities offered by the\nErasmus+ scheme.", "positive": "High-order Discontinuous Galerkin hydrodynamics with sub-cell shock\n capturing on GPUs: Hydrodynamical numerical methods that converge with high-order hold\nparticular promise for astrophysical studies, as they can in principle reach\nprescribed accuracy goals with higher computational efficiency than standard\nsecond- or third-order approaches. Here we consider the performance and\naccuracy benefits of Discontinuous Galerkin (DG) methods, which offer a\nparticularly straightforward approach to reach extremely high order. Also,\ntheir computational stencil maps well to modern GPU devices, further raising\nthe attractiveness of this approach. However, a traditional weakness of this\nmethod lies in the treatment of physical discontinuities such as shocks. We\naddress this by invoking an artificial viscosity field to supply required\ndissipation where needed, and which can be augmented, if desired, with physical\nviscosity and thermal conductivity, yielding a high-order treatment of the\nNavier-Stokes equations for compressible fluids. We show that our approach\nresults in sub-cell shock capturing ability, unlike traditional limiting\nschemes that tend to defeat the benefits of going to high order in DG in\nproblems featuring many shocks. We demonstrate exponential convergence of our\nsolver as a function of order when applied to smooth flows, such as the\nKelvin-Helmholtz reference problem of arXiv:1509.03630. We also demonstrate\nexcellent scalability of our GPU implementation up to hundreds of GPUs\ndistributed on different compute nodes. In a first application to driven,\nsub-sonic turbulence, we highlight the accuracy advantages of high-order DG\ncompared to traditional second-order accurate methods, and we stress the\nimportance of physical viscosity for obtaining accurate velocity power spectra." }, { "anchor": "Virtual Observatory for Astronomers: Where Are We Now?: After several years of intensive technological development Virtual\nObservatory resources have reached a level of maturity sufficient for their\nroutine scientific exploitation. The Virtual Observatory is starting to be used\nby astronomers in a transparent way. In this article I will review several\nresearch projects making use of the VO at different levels of importance. I\nwill present two projects going further than data mining: (1) studies of\nenvironmental effects on galaxy evolution, where VO resources and services are\nused in connection with dedicated observations using a large telescope and\nnumerical simulations, and (2) a study of optical and near-infrared colours of\nnearby galaxies complemented by the spectroscopic data.", "positive": "Correlation between the phase and the log-amplitude of a wave through\n the vertical atmospheric propagation: Expressions of the correlation between the log-amplitude and the phase of a\nwavefront propagating through the atmospheric turbulence are presented. These\nexpressions are useful to evaluate the feasibility of proposed methods to\nincrease the confidence level of the detection of faint transient astronomical\nobjects. The properties of the derived angular correlation functions are\ndiscussed using usual synthetic turbulence profiles. The close formulation\nbetween the phase and the log-amplitude allows an analytic formulation in the\nRytov approximation. Equations contain the product of an arbitrary number of\nhypergeometric functions that are evaluated using the Mellin transforms\nintegration method." }, { "anchor": "Revisitation of time delay interferometry combinations that suppress\n laser noise in LISA: With the purpose of understanding how time delay interferometry (TDI)\ncombinations can best be used for the characterisation of LISA instrumental\nnoise, we revisit their laser frequency noise cancellation properties. We have\ndeveloped an algorithm to search for all possible combinations that suppress\nnoise at the same level as the X, Y and Z classical combination. The algorithm\ncalculates delays using symbolic formulas that explicitly include velocities\nand accelerations of satellites up to the relevant order. In addition, once a\ncombination has been identified, delays are verified by solving numerically the\nrelevant equations using Keplerian orbits and Shapiro delay corrections. We\nfind that the number of combinations that suppress the noise is larger than\nwhat was reported in the literature. In particular we find that some\ncombinations that were thought to only partly suppress the noise, in reality do\nsuppress it at the same level of accuracy as the basic X, Y and Z combinations.", "positive": "Mixing Sinc kernels to improve interpolations in smoothed particle\n hydrodynamics without pairing instability: The smoothed particle hydrodynamic technique is strongly based on the proper\nchoice of interpolation functions. This statement is particularly relevant for\nthe study of subsonic fluxes and turbulence, where inherent small errors in the\naveraging procedures introduce excessive damping on the smallest scales. To\nmitigate these errors we can increase both the number of interpolating points\nand the order of the interpolating kernel function. However, this approach\nleads to a higher computational burden across all fluid regions. Ideally, the\ndevelopment of a single kernel function capable of effectively accommodating\nvarying numbers of interpolating points in different fluid regions, providing\ngood resolution and minimal errors would be highly desirable. In this work, we\nrevisit and extend the main properties of a family of interpolators called\n$Sinc~kernels$ and compare them with the widely used family of Wendland\nkernels. We show that a linear combination of low- and high-order Sinc kernels\ngenerates good-quality interpolators, which are resistant to pairing\ninstability while maintaining good sampling properties in a wide range of\nneighbor interpolating points, $60\\le n_b\\le 400$. We show that a particular\ncase of this linear mix of Sincs produces a well-balanced and robust kernel\nthat improves previous results in the Gresho-Chan vortex experiment even when\nthe number of neighbors is not large, while yielding a good convergence rate.\nAlthough such a mixing technique is ideally suited for Sinc kernels owing to\ntheir excellent flexibility, it can be easily applied to other interpolating\nfamilies such as the B-splines and Wendland kernels." }, { "anchor": "The Speedster-EXD- A New Event-Driven Hybrid CMOS X-ray Detector: The Speedster-EXD is a new 64x64 pixel, 40 $\\mu$m pixel pitch, 100 $\\mu$m\ndepletion depth hybrid CMOS X-ray detector (HCD) with the capability of reading\nout only those pixels containing event charge, thus enabling fast effective\nframe rates. A global charge threshold can be specified, and pixels containing\ncharge above this threshold are flagged and read out. The Speedster detector\nhas also been designed with other advanced in-pixel features to improve\nperformance, including a low-noise, high-gain CTIA amplifier that eliminates\ninterpixel capacitance crosstalk (IPC), and in-pixel Correlated Double Sampling\n(CDS) subtraction to reduce reset noise. We measure the best energy resolution\non the Speedster-EXD detector to be 206 eV (3.5 %) at 5.89 keV and 172 eV (10.0\n%) at 1.49 keV. The average IPC to the four adjacent pixels is measured to be\n0.25 $\\pm$ 0.2 % (i.e. consistent with zero). The pixel-to-pixel gain variation\nis measured to be 0.80 $\\pm$ 0.03 %, and a Monte Carlo simulation is applied to\nbetter characterize the contributions to the energy resolution.", "positive": "MCMC to address model misspecification in Deep Learning classification\n of Radio Galaxies: The radio astronomy community is adopting deep learning techniques to deal\nwith the huge data volumes expected from the next-generation of radio\nobservatories. Bayesian neural networks (BNNs) provide a principled way to\nmodel uncertainty in the predictions made by deep learning models and will play\nan important role in extracting well-calibrated uncertainty estimates from the\noutputs of these models. However, most commonly used approximate Bayesian\ninference techniques such as variational inference and MCMC-based algorithms\nexperience a \"cold posterior effect (CPE)\", according to which the posterior\nmust be down-weighted in order to get good predictive performance. The CPE has\nbeen linked to several factors such as data augmentation or dataset curation\nleading to a misspecified likelihood and prior misspecification. In this work\nwe use MCMC sampling to show that a Gaussian parametric family is a poor\nvariational approximation to the true posterior and gives rise to the CPE\npreviously observed in morphological classification of radio galaxies using\nvariational inference based BNNs." }, { "anchor": "Collaborative visual analytics of radio surveys in the Big Data era: Radio survey datasets comprise an increasing number of individual\nobservations stored as sets of multidimensional data. In large survey projects,\nastronomers commonly face limitations regarding: 1) interactive visual\nanalytics of sufficiently large subsets of data; 2) synchronous and\nasynchronous collaboration; and 3) documentation of the discovery workflow. To\nsupport collaborative data inquiry, we present encube, a large-scale\ncomparative visual analytics framework. Encube can utilise advanced\nvisualization environments such as the CAVE2 (a hybrid 2D and 3D virtual\nreality environment powered with a 100 Tflop/s GPU-based supercomputer and 84\nmillion pixels) for collaborative analysis of large subsets of data from radio\nsurveys. It can also run on standard desktops, providing a capable visual\nanalytics experience across the display ecology. Encube is composed of four\nprimary units enabling compute-intensive processing, advanced visualisation,\ndynamic interaction, parallel data query, along with data management. Its\nmodularity will make it simple to incorporate astronomical analysis packages\nand Virtual Observatory capabilities developed within our community. We discuss\nhow encube builds a bridge between high-end display systems (such as CAVE2) and\nthe classical desktop, preserving all traces of the work completed on either\nplatform -- allowing the research process to continue wherever you are.", "positive": "Circular polarization measurement in millimeter-wavelength spectral-line\n VLBI observations: This paper considers the problem of accurate measurement of circular\npolarization in imaging spectral-line VLBI observations in the lambda=7 mm and\nlambda=3 mm wavelength bands. This capability is especially valuable for the\nfull observational study of compact, polarized SiO maser components in the\nnear-circumstellar environment of late-type, evolved stars. Circular VLBI\npolarimetry provides important constraints on SiO maser astrophysics, including\nthe theory of polarized maser emission transport, and on the strength and\ndistribution of the stellar magnetic field and its dynamical role in this\ncritical circumstellar region. We perform an analysis here of the data model\ncontaining the instrumental factors that limit the accuracy of circular\npolarization measurements in such observations, and present a corresponding\ndata reduction algorithm for their correction. The algorithm is an enhancement\nof existing spectral line VLBI polarimetry methods using autocorrelation data\nfor calibration, but with innovations in bandpass determination,\nautocorrelation polarization self-calibration, and general optimizations for\nthe case of low SNR, as applicable at these wavelengths. We present an example\ndata reduction at $\\lambda=7$ mm and derive an estimate of the predicted\naccuracy of the method of m_c < 0.5% or better at lambda=7 mm and m_c < 0.5-1%\nor better at lambda=3 mm. Both the strengths and weaknesses of the proposed\nalgorithm are discussed, along with suggestions for future work." }, { "anchor": "The case of 3C326: VLA 74 MHz observations during a geomagnetic storm: Reaching the thermal noise at low frequencies with the next generation of\ninstruments (e.g. SKA, LOFAR etc.) is going to be a challenge. It requires the\ndevelopment of more advanced techniques of calibration compared to those used\nfrom the traditional radio astronomy until now. This revolution has slowly\nstarted, from self-cal, going through field based correction and SPAM up to the\nformulation and application of a general Measurement Equation. We will describe\nand compare the several approaches of calibration used so far to reduce low\nfrequency data. We will present some results of a 74 MHz VLA observation in\nexceptional ionospheric conditions of the giant radio galaxy 3C326 for which\nsome of these methods have been successfully applied.", "positive": "Millimeter Wave and Terahertz Spectra and Global Fit of Torsion-Rotation\n Transitions in the Ground, First and Second Excited Torsional States of\n 13CH3OH Methanol: Methanol is observed in a wide range of astrophysical sources throughout the\nuniverse, and comprehensive databases of the millimeter and THz spectra of\nCH3OH and its principal isotopologues represent important tools for the\nastronomical community. A previous combined analysis of microwave and\nmillimeter wave spectra of 13CH3OH together with Fourier transform far-infrared\nspectra was limited to the first two torsional states, v_t = 0 and 1, for J\nvalues up to 20. The limits on frequency and quantum number coverage have\nrecently been extended by new millimeter and THz measurements on several\ndifferent spectrometers in the Cologne laboratory in the frequency windows\n34-70 GHz, 75-120 GHz, 240-340 GHz, 360-450 GHz and 1.12-1.50 THz. With the new\ndata, the global treatment has now been expanded to include the first three\ntorsional states for J values up to 30. The current 13CH3OH data set contains\nabout 2,300 microwave, millimeter-wave, sub-millimeter and THz lines and about\n17,100 Fourier-transform far-infrared lines, representing the most recent\navailable information in the quantum number ranges J 10^{16}$eV following Earth-skimming trajectories. The\n$\\sim1^{\\circ}$ beaming of the radio emission in the forward direction however\nimplies that the radio signal will likely fly above a detector deployed over a\nflat site and would therefore not be detected. We study here how a non-flat\ndetector topography can improve the detection probability of these\nneutrino-induced air showers. We do this by computing with three distinct tools\nthe neutrino detection efficiency for a radio array deployed over a toy-model\nmountainous terrain, also taking into account experimental and topographic\nconstraints. We show in particular that ground topographies inclined by few\ndegrees only induce detection efficiencies typically three times larger than\nthose obtained for flat areas for favorable trajectories. We conclude that the\ntopography of the area where the detector is deployed will be a key factor for\nan experiment like GRAND.", "positive": "The Application of Cloud Computing to the Creation of Image Mosaics and\n Management of Their Provenance: We have used the Montage image mosaic engine to investigate the cost and\nperformance of processing images on the Amazon EC2 cloud, and to inform the\nrequirements that higher-level products impose on provenance management\ntechnologies. We will present a detailed comparison of the performance of\nMontage on the cloud and on the Abe high performance cluster at the National\nCenter for Supercomputing Applications (NCSA). Because Montage generates many\nintermediate products, we have used it to understand the science requirements\nthat higher-level products impose on provenance management technologies. We\ndescribe experiments with provenance management technologies such as the\n\"Provenance Aware Service Oriented Architecture\" (PASOA)." }, { "anchor": "A Serendipitous MWA Search for Narrow-band and Broad-band Low Frequency\n Radio Transmissions from 1I/2017 U1 'Oumuamua: We examine data from the Murchison Widefield Array (MWA) in the frequency\nrange 72 -- 102 MHz for a field-of-view that serendipitously contained the\ninterstellar object 'Oumuamua on 2017 November 28. Observations took place with\ntime resolution of 0.5 s and frequency resolution of 10 kHz. %This observation\nwas undertaken for another purpose but due to the MWA's extremely large\nfield-of-view, 'Oumuamua was serendipitously observed simultaneously. Based on\nthe interesting but highly unlikely suggestion that 'Oumuamua is an\ninterstellar spacecraft, due to some unusual orbital and morphological\ncharacteristics, we examine our data for signals that might indicate the\npresence of intelligent life associated with 'Oumuamua. We searched our radio\ndata for: 1) impulsive narrow-band signals; 2) persistent narrow-band signals;\nand 3) impulsive broadband signals. We found no such signals with\nnon-terrestrial origins and make estimates of the upper limits on Equivalent\nIsotropic Radiated Power (EIRP) for these three cases of approximately 7 kW,\n840 W, and 100 kW, respectively. These transmitter powers are well within the\ncapabilities of human technologies, and are therefore plausible for alien\ncivilizations. While the chances of positive detection in any given Search for\nExtraterrestrial Intelligence (SETI) experiment are vanishingly small, the\ncharacteristics of new generation telescopes such as the MWA (and in the\nfuture, the Square Kilometre Array) make certain classes of SETI experiment\neasy, or even a trivial by-product of astrophysical observations. This means\nthat the future costs of SETI experiments are very low, allowing large target\nlists to partially balance the low probability of a positive detection.", "positive": "FlashCam: A fully digital camera for CTA telescopes: The future Cherenkov Telescope Array (CTA) will consist of several tens of\ntelescopes of different mirror sizes. CTA will provide next generation\nsensitivity to very high energy photons from few tens of GeV to >100 TeV.\nSeveral focal plane instrumentation options are currently being evaluated\ninside the CTA consortium. In this paper, the current status of the FlashCam\nprototyping project is described. FlashCam is based on a fully digital camera\nreadout concept and features a clean separation between photon detector plane\nand signal digitization/triggering electronics." }, { "anchor": "HERITAGE: a Monte Carlo code to evaluate the viability of interstellar\n travels using a multi-generational crew: To evaluate the feasibility of long duration, manned spaceflights, it is of\ncritical importance to consider the selection and survival of\nmulti-generational crews in a confined space. Negative effects, such as\ninfertility, overpopulation and inbreeding, can easily cause the crew to either\nbe wiped out or genetically unhealthy, if the population is not under a strict\nbirth control. In this paper, we present a Monte Carlo code named HERITAGE that\nsimulates the evolution of a kin-based crew. This computer model, the first of\nits kind, accounts for a large number of free human-based parameters to be\ninvestigated proactively in order to ensure a viable mission. We show the\nreliability of HERITAGE by examining three types of population based on\npreviously published computations. The first is a generic model where no\nbirth/population control has been set up, quickly leading to fatal\novercrowding. The second is the model presented by Moore (2003), that succeeds\nto bring settlers to another Earth under a 200 year-long flight, but the final\ncrew is largely diminished (about a third of the initial crew) and about 20% of\nthem show inbreeding of various levels. The third scenario is the model by\nSmith (2014) that is more successful in maintaining genetic diversity for the\nsame journey duration. We find that both the Moore and Smith scenario would\ngreatly benefit from coupling a kin-based crew together with a cryogenic bank\nof sperm/eggs/embryos to ensure a genetically healthy first generation of\nsettlers. We also demonstrate that if initial social engineering constraints\nare indeed needed to maintain an healthy crew alive for centuries-long\njourneys, it is necessary to reevaluate those principles after each generation\nto compensate for unbalanced births and deaths, weighted by the inbreeding\ncoefficient and a need for maximizing genetic diversity.", "positive": "Techniques for Measuring Aerosol Attenuation using the Central Laser\n Facility at the Pierre Auger Observatory: The Pierre Auger Observatory in Malarg\\\"ue, Argentina, is designed to study\nthe properties of ultra-high energy cosmic rays with energies above 1018 eV. It\nis a hybrid facility that employs a Fluorescence Detector to perform nearly\ncalorimetric measurements of Extensive Air Shower energies. To obtain reliable\ncalorimetric information from the FD, the atmospheric conditions at the\nobservatory need to be continuously monitored during data acquisition. In\nparticular, light attenuation due to aerosols is an important atmospheric\ncorrection. The aerosol concentration is highly variable, so that the aerosol\nattenuation needs to be evaluated hourly. We use light from the Central Laser\nFacility, located near the center of the observatory site, having an optical\nsignature comparable to that of the highest energy showers detected by the FD.\nThis paper presents two procedures developed to retrieve the aerosol\nattenuation of fluorescence light from CLF laser shots. Cross checks between\nthe two methods demonstrate that results from both analyses are compatible, and\nthat the uncertainties are well understood. The measurements of the aerosol\nattenuation provided by the two procedures are currently used at the Pierre\nAuger Observatory to reconstruct air shower data." }, { "anchor": "Basic Testing of the Duchamp Source Finder: This paper presents and discusses the results of basic source finding tests\nin three dimensions (using spectroscopic data cubes) with Duchamp, the standard\nsource finder for the Australian SKA Pathfinder. For this purpose, we generated\ndifferent sets of unresolved and extended HI model sources. These models were\nthen fed into Duchamp, using a range of different parameters and methods\nprovided by the software. The main aim of the tests was to study the\nperformance of Duchamp on sources with different parameters and morphologies\nand assess the accuracy of Duchamp's source parametrisation. Overall, we find\nDuchamp to be a powerful source finder capable of reliably detecting sources\ndown to low signal-to-noise ratios and accurately measuring their position and\nvelocity. In the presence of noise in the data, Duchamp's measurements of basic\nsource parameters, such as spectral line width and integrated flux, are\naffected by systematic errors. These errors are a consequence of the effect of\nnoise on the specific algorithms used by Duchamp for measuring source\nparameters in combination with the fact that the software only takes into\naccount pixels above a given flux threshold and hence misses part of the flux.\nIn scientific applications of Duchamp these systematic errors would have to be\ncorrected for. Alternatively, Duchamp could be used as a source finder only,\nand source parametrisation could be done in a second step using more\nsophisticated parametrisation algorithms.", "positive": "Point source calibration of the AKARI/FIS all-sky survey maps for\n staking analysis: Investigations of the point spread functions (PSFs) and flux calibrations for\nstacking analysis have been performed with the far-infrared (wavelengths range\nof 60 to 140 um all-sky maps taken by the Far-Infrared Surveyor (FIS) onboard\nthe AKARI satellite. The PSFs are investigated by stacking the maps at the\npositions of standard stars with their fluxes of 0.02 -10 Jy. The derived full\nwidths at the half maximum (FWHMs) of the PSFs are ~ 60 arcsec at 65 and 90 um\nand ~ 90 arcsec at 140 um, which are much smaller than that of the previous\nall-sky maps obtained with IRAS (~ 6 arcmin). Any flux dependence in the PSFs\nis not seen on the investigated flux range. By performing the flux\ncalibrations, we found that absolute photometry for faint sources can be\ncarried out with constant calibration factors, which range from 0.6 to 0.8.\nAfter applying the calibration factors, the photometric accuracies for the\nstacked sources in the 65, 90, and 140 um bands are 9, 3, and 21 %,\nrespectively, even below the detection limits of the survey. Any systematic\ndependence between the observed flux and model flux is not found. These results\nindicate that the FIS map is a useful dataset for the stacking analyses of\nfaint sources at far-infrared wavelengths." }, { "anchor": "Next-generation Astronomy: Fundamental changes are taking place in the way we do astronomy. In twenty\nyears time, it is likely that most astronomers will never go near a\ncutting-edge telescope, which will be much more efficiently operated in service\nmode. They will rarely analyse data, since all the leading-edge telescopes will\nhave pipeline processors. And rather than competing to observe a particularly\ninteresting object, astronomers will more commonly group together in large\nconsortia to observe massive chunks of the sky in carefully designed surveys,\ngenerating petabytes of data daily.\n We can imagine that astronomical productivity will be higher than at any\nprevious time. PhD students will mine enormous survey databases using\nsophisticated tools, cross-correlating different wavelength data over vast\nareas, and producing front-line astronomy results within months of starting\ntheir PhD. The expertise that now goes into planning an observation will\ninstead be devoted to planning a foray into the databases. In effect, people\nwill plan observations to use the Virtual Observatory. Here I examine the\nprocess of astronomical discovery, take a crystal ball to see how it might\nchange over the next twenty years, and identify further opportunities for the\nfuture, as well as identifying pitfalls against which we must remain vigilant.", "positive": "EOVSA Implementation of a Spectral Kurtosis Correlator for Transient\n Detection and Classification: We describe in general terms the practical use in astronomy of a higher-order\nstatistical quantity called Spectral Kurtosis (SK), and describe the first\nimplementation of SK-enabled firmware in the F-engine (Fourier\ntransform-engine) of a digital FX correlator for Expanded Owens Valley Solar\nArray (EOVSA). The development of the theory for SK is summarized, leading to\nan expression for generalized SK that is applicable to both SK spectrometers\nand those not specifically designed for SK. We also give the means for\ncomputing both the SK estimator and thresholds for its application as a\ndiscriminator of RFI contamination. Tests of the performance of EOVSA as an SK\nspectrometer are shown to agree precisely with theoretical expectations, and\nthe methods for configuring the correlator for correct SK operation are\ndescribed." }, { "anchor": "The Enhanced Resolution Imager and Spectrograph for the VLT: ERIS, the Enhanced Resolution Imager and Spectrograph, is an instrument that\nboth extends and enhances the fundamental diffraction limited imaging and\nspectroscopy capability for the VLT. It replaces two instruments that were\nbeing maintained beyond their operational lifetimes, combines their\nfunctionality on a single focus, provides a new wavefront sensing module for\nnatural and laser guide stars that makes use of the Adaptive Optics Facility,\nand considerably improves on their performance. The observational modes ERIS\nprovides are integral field spectroscopy at 1-2.5 {\\mu}m, imaging at 1-5 {\\mu}m\nwith several options for high contrast imaging, and longslit spectroscopy at\n3-4 {\\mu}m, The instrument is installed at the Cassegrain focus of UT4 at the\nVLT and, following its commissioning during 2022, has been made available to\nthe community.", "positive": "Normalizing Flows for Hierarchical Bayesian Analysis: A Gravitational\n Wave Population Study: We propose parameterizing the population distribution of the gravitational\nwave population modeling framework (Hierarchical Bayesian Analysis) with a\nnormalizing flow. We first demonstrate the merit of this method on illustrative\nexperiments and then analyze four parameters of the latest LIGO/Virgo data\nrelease: primary mass, secondary mass, redshift, and effective spin. Our\nresults show that despite the small and notoriously noisy dataset, the\nposterior predictive distributions (assuming a prior over the parameters of the\nflow) of the observed gravitational wave population recover structure that\nagrees with robust previous phenomenological modeling results while being less\nsusceptible to biases introduced by less flexible models. Therefore, the method\nforms a promising flexible, reliable replacement for population inference\ndistributions, even when data is highly noisy." }, { "anchor": "The capabilities and performance of the Automated Planet Finder\n Telescope with the implementation of a dynamic scheduler: We report initial performance results emerging from 600 hours of observations\nwith the Automated Planet Finder (APF) telescope and Levy Spectrometer located\nat UCO/Lick Observatory. We have obtained multiple spectra of 80 G, K and\nM-type stars, which comprise 4,954 individual Doppler radial velocity (RV)\nmeasurements with a median internal uncertainty of 1.35 ms$^{-1}$. We find a\nstrong, expected correlation between the number of photons accumulated in the\n5000-6200$\\AA$ iodine region of the spectrum, and the resulting internal\nuncertainty estimates. Additionally, we find an offset between the population\nof G and K stars and the M stars within the data set when comparing these\nparameters. As a consequence of their increased spectral line densities, M-type\nstars permit the same level of internal uncertainty with 2x fewer photons than\nG-type and K-type stars. When observing M stars, we show that the APF/Levy has\nessentially the same speed-on-sky as Keck/HIRES for precision RVs. In the\ninterest of using the APF for long-duration RV surveys, we have designed and\nimplemented a dynamic scheduling algorithm. We discuss the operation of the\nscheduler, which monitors ambient conditions and combines on-sky information\nwith a database of survey targets to make intelligent, real-time targeting\ndecisions.", "positive": "An H-band Vector Vortex Coronagraph for the Subaru Coronagraphic\n Extreme-Adaptive Optics System: The vector vortex is a coronagraphic imaging mode of the recently\ncommissioned Subaru Coronagraphic Extreme-Adaptive Optics (SCExAO) platform on\nthe 8-m Subaru Telescope. This multi-purpose high-contrast visible and\nnear-infrared (R- to K-band) instrument is not only intended to serve as a\nVLT-class \"planet-imager\" instrument in the Northern hemisphere, but also to\noperate as a technology demonstration testbed ahead of the ELTs-era, with a\nparticular emphasis on small inner-working angle (IWA) coronagraphic\ncapabilities. The given priority to small-IWA imaging led to the early design\nchoice to incorporate focal-plane phase-mask coronagraphs. In this context, a\ntest H-band vector vortex liquid crystal polymer waveplate was provided to\nSCExAO, to allow a one-to-one comparison of different small-IWA techniques on\nthe same telescope instrument, before considering further steps. Here we\npresent a detailed overview of the vector vortex coronagraph, from its\ninstallation and performances on the SCExAO optical bench, to the on-sky\nresults in the extreme AO regime, as of late 2016/early 2017. To this purpose,\nwe also provide a few recent on-sky imaging examples, notably high-contrast ADI\ndetection of the planetary-mass companion \\kappa Andromedae b, with a\nsignal-to-noise ratio above 100 reached in less than 10 mn exposure time." }, { "anchor": "Low-cost, Low-loss, Ultra-wideband Compact Feed for Interferometric\n Radio Telescopes: We have developed, built, and tested a new feed design for interferometric\nradio telescopes with \"large-$N$, small-$D$\" designs. Those arrays require\nlow-cost and low-complexity feeds for mass production on reasonable timescales\nand budgets, and also require those feeds to be compact to minimize obstruction\nof the dishes, along with having ultra wide bands of operation for most current\nand future science goals. The feed presented in this paper modifies the\nexponentially tapered slot antenna (Vivaldi) and quad-ridged flared horn\nantenna designs by having an oversized backshort, a novel method of maintaining\na small size that is well-suited for deeper dishes ($f/D\\leq 0.25$). It is made\nof laser cut aluminum and printed circuit boards, such that it is inexpensive\n($\\lesssim$ 75 USD per feed in large-scale production) and quick to build; it\nhas a 5:1 frequency ratio, and its size is approximately a third of its longest\noperating wavelength. We present the science and engineering constraints that\nwent into design decisions, the development and optimization process, and the\nsimulated performance. A version of this feed design was optimized and built\nfor the Canadian Hydrogen Observatory and Radio-transient Detector (CHORD)\nprototypes. When simulated on CHORD's very deep dishes ($f/D=0.21$) and with\nCHORD's custom first stage amplifiers, the on-sky system temperature\n$T_\\mathrm{sys}$ of the complete receiving system from dish to digitizer\nremains below 30 K over most of the 0.3-1.5 GHz band, and maintains an aperture\nefficiency $\\eta_\\mathrm{A}$ between 0.4 and 0.6. The entire receiving chain\noperates at ambient temperature. The feed is designed to slightly\nunder-illuminate the CHORD dishes, in order to minimize coupling between array\nelements and spillover.", "positive": "Using artificial neural networks to improve photometric modeling in\n airless bodies: Relevant information about physical properties of the surface of airless\nbodies such as porosity, particle size, or roughness can be inferred knowing\nthe dependence of the brightness with illumination and observing geometry.\nAdditionally, this knowledge is necessary to standardize or photometrically\ncorrect data acquired under different illumination conditions. In this work we\ndevelop a robust, automatic, and efficient photometric modeling methodology\nwhich is tested and validated using Bennu images acquired by the camera MapCam\nfrom the OSIRIS-REx spacecraft. It consists of a supervised machine learning\nalgorithm through an artificial neural network. Our system provides a more\nprecise modeling for all color filters than the previous procedures which are\nalready published, offering an improvement over this classic approach of up to\n14.30%, as well as a considerable reduction in computing time." }, { "anchor": "Boost recall in QSO selection from highly imbalanced photometric\n datasets: Context. The identification of bright QSOs is of great importance to probe\nthe intergalactic medium and address open questions in cosmology. Several\napproaches have been adopted to find such sources in currently available\nphotometric surveys, including machine learning methods. However, the rarity of\nbright QSOs at high redshifts compared to contaminating sources (such as stars\nand galaxies) makes the selection of reliable candidates a difficult task,\nespecially when high completeness is required. Aims. We present a novel\ntechnique to boost recall (i.e., completeness within the considered sample) in\nthe selection of QSOs from photometric datasets dominated by stars, galaxies,\nand low-z QSOs (imbalanced datasets). Methods. Our method operates by\niteratively removing sources whose probability of belonging to a noninteresting\nclass exceeds a user-defined threshold, until the remaining dataset contains\nmainly high-z QSOs. Any existing machine learning method can be used as\nunderlying classifier, provided it allows for a classification probability to\nbe estimated. We applied the method to a dataset obtained by cross-matching\nPanSTARRS1, Gaia, and WISE, and identified the high-z QSO candidates using both\nour method and its direct multi-label counterpart. Results. We ran several\ntests by randomly choosing the training and test datasets, and achieved\nsignificant improvements in recall which increased from 50% to 85% for QSOs\nwith z>2.5, and from 70% to 90% for QSOs with z>3. Also, we identified a sample\nof 3098 new QSO candidates on a sample of 2.6x10^6 sources with no known\nclassification. We obtained follow-up spectroscopy for 121 candidates,\nconfirming 107 new QSOs with z>2.5. Finally, a comparison of our candidates\nwith those selected by an independent method shows that the two samples overlap\nby more than 90% and that both methods are capable of achieving a high level of\ncompleteness.", "positive": "An update of the on-sky performance of the Layer-Oriented wave-front\n sensor for MAD: The Multi-conjugate Adaptive optics Demonstrator, MAD, successfully\ndemonstrated on sky the MCAO technique both in Layer Oriented and Star Oriented\nmodes. As results of the Guaranteed Time Observations in Layer Oriented mode\nquality astronomy papers have been published. In this paper we concentrate on\nthe instrumentation issues and technical aspects which stay behind this\nsuccess." }, { "anchor": "Atmospheric Extinction Coefficients and Night Sky Brightness At the Xuyi\n Observational Station: We present measurements of the optical broadband atmospheric extinction\ncoefficients and the night sky brightness at the Xuyi Observational Station of\nPurple Mountain Observatory (PMO). The measurements are based on CCD imaging\ndata taken in the Sloan Digital Sky Survey g, r and i bands with the Xuyi\n1.04/1.20m Schmidt Telescope for the Xuyi Schmidt Telescope Photometric Survey\nof the Galactic Anti-center (XSTPS-GAC), the photometric part of the Digital\nSky Survey of the Galactic Anti-center (DSS-GAC). The data were collected in\nmore than 130 winter nights from 2009 to 2011. We find that the atmospheric\nextinction coefficients for the g, r and i bands are 0.70, 0.55 and 0.38\nmag/airmass, respectively, based on observations taken in several photometric\nnights. The night sky brightness determined from images of good quality has\nmedian val- ues of 21.7, 20.8 and 20.0 mag/arcsec2 and reaches 22.1, 21.2 and\n20.4 mag/arcsec2 under the best observing conditions for the g, r and i bands,\nrespectively. The relatively large extinction coefficients compared with other\ngood astronomical observing sites are mainly due to the relatively low\nelevation (i.e. 180 m) and high humidity of the Station.", "positive": "The Simons Observatory: Magnetic Sensitivity Measurements of Microwave\n SQUID Multiplexers: The Simons Observatory (SO) will be a cosmic microwave background (CMB)\nsurvey experiment with three small-aperture telescopes and one large-aperture\ntelescope, which will observe from the Atacama Desert in Chile. In total, SO\nwill field $\\sim$70,000 transition-edge sensor (TES) bolometers in six spectral\nbands centered between 27 and 280 GHz in order to achieve the sensitivity\nnecessary to measure or constrain numerous cosmological quantities. The SO\nUniversal Focal Plane Modules (UFMs) each contain a 150 mm diameter TES\ndetector array, horn or lenslet optical coupling, cold readout components, and\nmagnetic shielding. SO will use a microwave SQUID multiplexing ($\\mu$MUX)\nreadout at an initial multiplexing factor of $\\sim$1000; the cold (100 mK)\nreadout components are packaged in a $\\mu$MUX readout module, which is part of\nthe UFM, and can also be characterized independently. The 100 mK stage TES\nbolometer arrays and microwave SQUIDs are sensitive to magnetic fields, and\ntheir measured response will vary with the degree to which they are\nmagnetically shielded. We present measurements of the magnetic pickup of test\nmicrowave SQUID multiplexers as a study of various shielding configurations for\nthe Simons Observatory. We discuss how these measurements motivated the\nmaterial choice and design of the UFM magnetic shielding." }, { "anchor": "The Topo-trigger: a new concept of stereo trigger system for imaging\n atmospheric Cherenkov telescopes: Imaging atmospheric Cherenkov telescopes (IACTs) such as the Major\nAtmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes endeavor to reach\nthe lowest possible energy threshold. In doing so the trigger system is a key\nelement. Reducing the trigger threshold is hampered by the rapid increase of\naccidental triggers generated by ambient light, the so-called Night Sky\nBackground (NSB). In this paper we present a topological trigger, dubbed\nTopo-trigger, which rejects events on the basis of their relative orientation\nin the telescope cameras. We have simulated and tested the trigger selection\nalgorithm in the MAGIC telescopes. The algorithm was tested using MonteCarlo\nsimulations and shows a rejection of 85% of the accidental stereo triggers\nwhile preserving 99 % of the gamma rays. A full implementation of this trigger\nsystem would achieve an increase in collection area between 10 and 20% at the\nenergy threshold. The analysis energy threshold of the instrument is expected\nto decrease by ~8 %. The selection algorithm was tested on real MAGIC data\ntaken with the current trigger configuration and no $\\gamma$-like events were\nfound to be lost.", "positive": "Observing, calibrating and reducing near-infrared imaging mosaics: In near-infrared bands, co-adding and tiling of astronomical imaging datasets\nrequire a sufficiently high calibration quality (flat fielding, background\nsubtraction). Here we present a complete workflow for obtaining imaging mosaics\nwith the MMT and Magellan Infrared Spectrograph (MMIRS) operated at the 6.5-m\nMMT in Arizona and open-source add-on tools developed for the MMIRS pipeline\nfor preparation and data reduction of mosaic observations. We describe\npre-observing actions, such as design of dithering patterns and mosaic layouts\nand post-processing steps to perform absolute astrometric and photometric\ncalibration, and also generate HiPS maps to display the final data product in\nAladin / Aladin Lite." }, { "anchor": "The GSO Data Centre: Hereafter we describe the activities of the $Grand \\, Sud-Ouest$ Data Centre\noperated for INSU/CNRS by the OMP-IRAP and the Universit\\'e Paul Sabatier\n(Toulouse), in a collaboration with the OASU-LAB (Bordeaux) and OREME-LUPM\n(Montpellier).", "positive": "Fresnel zone plate telescopes for X-ray imaging I: experiments with a\n quasi-parallel beam: Combination of Fresnel Zone Plates (FZP) can make an excellent telescope for\nimaging in X-rays. We present here the results of our experiments with several\npairs of tungsten made Fresnel Zone plates in presence of an X-ray source kept\nat a distance of about 45 feet. The quasi-parallel beam allowed us to study\nsources placed on the axis as well as off the axis of the telescope. We present\ntheoretical study of the fringe patterns produced by the zone plates in\npresence of a quasi-parallel source. We compare the patterns obtained from\nexperiments with those obtained by our Monte-Carlo simulations. The images are\nalso reconstructed by deconvolution from both the patterns. We compare the\nperformance of such a telescope with other X-ray imaging devices used in\nspace-astronomy." }, { "anchor": "MUPHOTEN : a MUlti-band PHOtometry Tool for TElescope Network: The early and complete temporal characterization of optical, fast, transient\nsources requires continuous and multiband observations over different\ntimescales (hours to months). For time-domain astronomy, using several\ntelescopes to analyze single objects is the usual method, allowing the\nacquisition of highly sampled light curves. Taking a series of images each\nnight helps to construct an uninterrupted chain of observations with a high\ncadence and low duty cycle. Speed is paramount, especially at early times, in\norder to capture early features in the light curve that help determine the\nnature of the observed transients and assess their astrophysical properties.\nHowever, the problem of rapidly extracting source properties (temporal and\ncolor evolution) with a heterogeneous data set remains. Consequently, we\npresent Muphoten, a general and fast-computation photometric pipeline able to\naddress these constraints. It is suitable for extracting transient brightness\nover multi-telescope and multiband networks to create a single homogeneous\nphotometric time series. We show the performance of Muphoten with observations\nof the optical transient SN 2018cow (from 2018 June to 2018 July), monitored by\nthe GRANDMA network and with the publicly available data of the Liverpool\nTelescope.", "positive": "Advances in the RXTE Proportional Counter Array Calibration: Nearing the\n Statistical Limit: During its 16 years of service the Rossi X-ray Timing Explorer (RXTE) mission\nhas provided an extensive archive of data, which will serve as a primary source\nof high cadence observations of variable X-ray sources for fast timing studies.\nIt is, therefore, very important to have the most reliable calibration of RXTE\ninstruments. The Proportional Counter Array (PCA) is the primary instrument\non-board RXTE which provides data in 3-50 keV energy range with sub-millisecond\ntime resolution in up to 256 energy channels. In 2009 the RXTE team revised the\nresponse residual minimization method used to derive the parameters of the PCA\nphysical model. The procedure is based on the residual minimization between the\nmodel spectrum for Crab nebula emission and a calibration data set consisting\nof a number of spectra from the Crab and the on-board Am241 calibration source,\nuniformly covering the whole RXTE mission operation period. The new method led\nto a much more effective model convergence and allowed for better understanding\nof the PCA energy-to-channel relationship. It greatly improved the response\nmatrix performance. We describe the new version of the RXTE/PCA response\ngenerator PCARMF v11.7 (HEASOFT Release 6.7) along with the corresponding\nenergy-to-channel conversion table (verson e05v04) and their difference from\nthe previous releases of PCA calibration. The new PCA response adequately\nrepresents the spectrum of the calibration sources and successfully predicts\nthe energy of the narrow iron emission line in Cas-A throughout the RXTE\nmission." }, { "anchor": "A Study on Mars Probe Failures: The long term dreams to approach Mars requires numerous spacecraft attempts\nfor exploration as well as to understand the perception of the red planet.\nBefore launching a mission, the space probe undergoes critical ground testing\nand effective preparation. Though probes were carefully tested and validated,\nmany experiences temporary or permanent setbacks prior to their final state of\nmission accomplishment, resulting in the failure of the mission. In order to\nfigure out the problems concerning probe malfunction or failure, we conducted a\nstudy on failed Mars probes that are launched between 1960 to 2020. The probes\nwere characterized to determine various modes of failure and their impact on\nthe missions. The results of our study from past probes showed effective\nintegration and testing, sterling fabrication and validation of space probes,\nadequate software design, feasible recovery options, and novel guidance to\nprobe computers and communication systems.", "positive": "Ionospheric Calibration of Low Frequency Radio Interferometric\n Observations using the Peeling Scheme: I. Method Description and First\n Results: Calibration of radio interferometric observations becomes increasingly\ndifficult towards lower frequencies. Below ~300 MHz, spatially variant\nrefractions and propagation delays of radio waves traveling through the\nionosphere cause phase rotations that can vary significantly with time, viewing\ndirection and antenna location. In this article we present a description and\nfirst results of SPAM (Source Peeling and Atmospheric Modeling), a new\ncalibration method that attempts to iteratively solve and correct for\nionospheric phase errors. To model the ionosphere, we construct a time-variant,\n2-dimensional phase screen at fixed height above the Earth's surface. Spatial\nvariations are described by a truncated set of discrete Karhunen-Loeve base\nfunctions, optimized for an assumed power-law spectral density of free\nelectrons density fluctuations, and a given configuration of calibrator sources\nand antenna locations. The model is constrained using antenna-based gain phases\nfrom individual self-calibrations on the available bright sources in the\nfield-of-view. Application of SPAM on three test cases, a simulated visibility\ndata set and two selected 74 MHz VLA data sets, yields significant improvements\nin image background noise (5-75 percent reduction) and source peak fluxes (up\nto 25 percent increase) as compared to the existing self-calibration and\nfield-based calibration methods, which indicates a significant improvement in\nionospheric phase calibration accuracy." }, { "anchor": "Deep Learning Unresolved Lensed Lightcurves: Gravitationally lensed sources may have unresolved or blended multiple\nimages, and for time varying sources the lightcurves from individual images can\noverlap. We use convolutional neural nets to both classify the lightcurves as\ndue to unlensed, double, or quad lensed sources and fit for the time delays.\nFocusing on lensed supernova systems with time delays $\\Delta t\\gtrsim6$ days,\nwe achieve 100\\% precision and recall in identifying the number of images and\nthen estimating the time delays to $\\sigma_{\\Delta t}\\approx1$ day, with a\n$1000\\times$ speedup relative to our previous Monte Carlo technique. This also\nsucceeds for flux noise levels $\\sim10\\%$. For $\\Delta t\\in[2,6]$ days we\nobtain 94--98\\% accuracy, depending on image configuration. We also explore\nusing partial lightcurves where observations only start near maximum light,\nwithout the rise time data, and quantify the success.", "positive": "Detecting multiple periodicities in observational data with the\n multifrequency periodogram - II. Frequency Decomposer, a parallelized\n time-series analysis algorithm: This is a parallelized algorithm performing a decomposition of a noisy time\nseries into a number of sinusoidal components. The algorithm analyses all\nsuspicious periodicities that can be revealed, including the ones that look\nlike an alias or noise at a glance, but later may prove to be a real variation.\nAfter selection of the initial candidates, the algorithm performs a complete\npass through all their possible combinations and computes the rigorous\nmultifrequency statistical significance for each such frequency tuple. The\nlargest combinations that still survived this thresholding procedure represent\nthe outcome of the analysis.\n The parallel computing on a graphics processing unit (GPU) is implemented\nthrough CUDA and brings a significant performance increase. It is still\npossible to run FREDEC solely on CPU in the traditional single-threaded mode,\nwhen no suitable GPU device is available.\n To verify the practical applicability of our algorithm, we apply it to an\nartificial time series as well as to some real-life exoplanetary\nradial-velocity data. We demonstrate that FREDEC can successfully reveal\nseveral known exoplanets. Moreover, it detected a new $9.8$-day variation in\nthe Lick data for the five-planet system of 55 Cnc. It might indicate the\nexistence of a small sixth planet in the 3:2 commensurability with the planet\n55 Cnc b, although this detection is model-dependent and still needs a detailed\nverification." }, { "anchor": "Hector - a new massively multiplexed IFS instrument for the\n Anglo-Australian Telescope: Hector will be the new massively-multiplexed integral field spectroscopy\n(IFS) instrument for the Anglo-Australian Telescope (AAT) in Australia and the\nnext main dark-time instrument for the observatory. Based on the success of the\nSAMI instrument, which is undertaking a 3400-galaxy survey, the integral field\nunit (IFU) imaging fibre bundle (hexabundle) technology under-pinning SAMI is\nbeing improved to a new innovative design for Hector. The distribution of\nhexabundle angular sizes is matched to the galaxy survey properties in order to\nimage 90% of galaxies out to 2 effective radii. 50-100 of these IFU imaging\nbundles will be positioned by 'starbug' robots across a new 3-degree field\ncorrector top end to be purpose-built for the AAT. Many thousand fibres will\nthen be fed into new replicable spectrographs. Fundamentally new science will\nbe achieved compared to existing instruments due to Hector's wider field of\nview (3 degrees), high positioning efficiency using starbugs, higher\nspectroscopic resolution (R~3000-5500 from 3727-7761A, with a possible redder\nextension later) and large IFUs (up to 30 arcsec diameter with 61-217 fibre\ncores). A 100,000 galaxy IFS survey with Hector will decrypt how the accretion\nand merger history and large-scale environment made every galaxy different in\nits morphology and star formation history. The high resolution, particularly in\nthe blue, will make Hector the only instrument to be able to measure\nhigher-order kinematics for galaxies down to much lower velocity dispersion\nthan in current large IFS galaxy surveys, opening up a wealth of new nearby\ngalaxy science.", "positive": "On-orbit performance of the Gaia CCDs at L2: The European Space Agency's Gaia satellite was launched into orbit around L2\nin December 2013 with a payload containing 106 large-format scientific CCDs.\nThe primary goal of the mission is to repeatedly obtain high-precision\nastrometric and photometric measurements of one thousand million stars over the\ncourse of five years. The scientific value of the down-linked data, and the\noperation of the onboard autonomous detection chain, relies on the high\nperformance of the detectors. As Gaia slowly rotates and scans the sky, the\nCCDs are continuously operated in a mode where the line clock rate and the\nsatellite rotation spin-rate are in synchronisation. Nominal mission operations\nbegan in July 2014 and the first data release is being prepared for release at\nthe end of Summer 2016.\n In this paper we present an overview of the focal plane, the detector system,\nand strategies for on-orbit performance monitoring of the system. This is\nfollowed by a presentation of the performance results based on analysis of data\nacquired during a two-year window beginning at payload switch-on. Results for\nparameters such as readout noise and electronic offset behaviour are presented\nand we pay particular attention to the effects of the L2 radiation environment\non the devices. The radiation-induced degradation in the charge transfer\nefficiency (CTE) in the (parallel) scan direction is clearly diagnosed;\nhowever, an extrapolation shows that charge transfer inefficiency (CTI) effects\nat end of mission will be approximately an order of magnitude less than\npredicted pre-flight. It is shown that the CTI in the serial register\n(horizontal direction) is still dominated by the traps inherent to the\nmanufacturing process and that the radiation-induced degradation so far is only\na few per cent. Finally, we summarise some of the detector effects discovered\non-orbit which are still being investigated." }, { "anchor": "Data Models for Radio Astronomy in the VO: Data Models are an essential part of automatic data processing, but even more\nso when trying to tie together data coming from many different data sources, as\nis the case for the International Virtual Observatory. In this talk we will\nreview the different data models used in the IVOA, which parts of that Data\nModelling work are still incomplete, specially in radio wavelengths, and the\nwork the AMIGA group has done within the IVOA Data Modelling Working Group to\novercome those shortcomings both in missing data models and support for Radio\nAstronomy.", "positive": "Influence of the Geomagnetic Field on the IACT detection technique for\n possible sites of CTA observatories: We investigate the influence of the geomagnetic field (GF) on the Imaging Air\nCherenkov Telescope technique for two northern (Tenerife and San Pedro Martir)\nand three southern (Salta, Leoncito and Namibia (the H.E.S.S.-site)) site\ncandidates for Cherenkov Telescope Array (CTA) observatories. We use the\nCORSIKA and sim_telarray programs for Monte Carlo simulations of gamma ray\nshowers, hadronic background and the telescope response. We focus here on gamma\nray measurements in the low energy, sub-100 GeV, range. Therefore, we only\nconsider the performance of arrays of several large telescopes. Neglecting the\nGF effect, we find (in agreement with previous studies) that such arrays have\nlower energy thresholds, and larger collection areas below 30 GeV, when located\nat higher altitudes. We point out, however, that in the considered ranges of\naltitudes and magnetic field intensities, 1800-3600 m a.s.l. and 0-40 uT,\nrespectively, the GF effect has a similar magnitude to this altitude effect. We\nprovide the trigger-level performance parameters of the observatory affected by\nthe GF effect, in particular the collection areas, detection rates and the\nenergy thresholds for all five locations, which information may be useful in\nthe selection of sites for CTA. We also find simple scaling of these parameters\nwith the magnetic field strength, which can be used to assess the magnitude of\nthe GF effect for other sites; in this work we use them to estimate the\nperformance parameters for five sites: South Africa-Beaufort West, USA-Yavapai\nRanch, Namibia-Lalapanzi, Chile-La Silla and India-Hanle. We roughly\ninvestigate the impact of the geophysical conditions on gamma/hadron separation\nprocedures involving image shape and direction cuts." }, { "anchor": "A Millimeter-wave Technique for correlation and beam combination for\n cosmology: We discuss new techniques and ideas in mm-wave instrumentation that can be\nused in CMB (Cosmic Microwave background) polarization experiments. Novel\ntechniques in antenna receiver, beam combining and detector systems have\nresulted in greatly improved sensitivities. We present a few promising\napproaches and discuss briefly plans for feasibility studies for detecting CMB\npolarization foregrounds and signal.", "positive": "Acrylic purification and coatings: Radon (Rn) and its decay daughters are a well-known source of background in\ndirect WIMP detection experiments, as either a Rn decay daughter or an alpha\nparticle emitted from a thin inner surface layer of a detector could produce a\nWIMP-like signal. Different surface treatment and cleaning techniques have been\nemployed in the past to remove this type of contamination. A new method of\ndealing with the problem has been proposed and used for a prototype acrylic\nDEAP-1 detector. Inner surfaces of the detector were coated with a layer of\nultra pure acrylic, meant to shield the active volume from alphas and recoiling\nnuclei. An acrylic purification technique and two coating techniques are\ndescribed: a solvent-borne (tested on DEAP-1) and solvent-less (being developed\nfor the full scale DEAP-3600 detector)." }, { "anchor": "Search for modulations of the solar Be-7 flux in the next-generation\n neutrino observatory LENA: A next-generation liquid-scintillator detector will be able to perform\nhigh-statistics measurements of the solar neutrino flux. In LENA, solar Be-7\nneutrinos are expected to cause 1.7x10^4 electron recoil events per day in a\nfiducial volume of 35 kilotons. Based on this signal, a search for periodic\nmodulations on sub-percent level can be conducted, surpassing the sensitivity\nof current detectors by at least a factor of 20. The range of accessible\nperiods reaches from several minutes, corresponding to modulations induced by\nhelioseismic g-modes, to tens of years, allowing to study long-term changes in\nsolar fusion rates.", "positive": "Interstellar Interferometry: Precise Curvature Measurement from Pulsar\n Secondary Spectra: The parabolic structure of the secondary or conjugate spectra of pulsars is\noften the result of isolated one-dimensional (or at least highly anisotropic)\nlenses in the ISM. The curvature of these features contains information about\nthe velocities of the Earth, ISM, and pulsar along the primary axis of the\nlens. As a result, measuring variations in the curvature over the course of a\nyear, or the orbital period for pulsars in binaries, can constrain properties\nof the screen and pulsar. In particular the pulsar distance and orbital\ninclination for binary systems can be found for multiple screens or systems\nwith prior information on $\\sin(i)$. By mapping the conjugate spectra into a\nspace where the main arc and inverted arclets are straight lines, we are able\nto make use of the full information content from the inverted arclet\ncurvatures, amplitudes, and phases using eigenvectors to uniquely and optimally\nretrieve phase information. This allows for a higher precision measurement than\nthe standard Hough transform for systems where these features are available.\nOur technique also directly yields the best fit 1D impulse response function\nfor the interstellar lens given in terms of the Doppler shift, time delay, and\nmagnification of images on the sky as seen from a single observatory. This can\nbe extended for use in holographic imaging of the lens by combining multiple\ntelescopes. We present examples of this new method for both simulated data and\nactual observations of PSR B0834+06." }, { "anchor": "The Impact of Interpixel Capacitance in CMOS Detectors on PSF shapes and\n Implications for WFIRST: Unlike optical CCDs, near-infrared detectors, which are based on CMOS hybrid\nreadout technology, typically suffer from electrical crosstalk between the\npixels. The interpixel capacitance (IPC) responsible for the crosstalk affects\nthe point-spread function (PSF) of the telescope, increasing the size and\nmodifying the shape of all objects in the images while correlating the Poisson\nnoise. Upcoming weak lensing surveys that use these detectors, such as WFIRST,\nplace stringent requirements on the PSF size and shape (and the level at which\nthese are known), which in turn must be translated into requirements on IPC. To\nfacilitate this process, we present a first study of the effect of IPC on\nWFIRST PSF sizes and shapes. Realistic PSFs are forward-simulated from physical\nprinciples for each WFIRST bandpass. We explore how the PSF size and shape\ndepends on the range of IPC coupling with pixels that are connected along an\nedge or corner; for the expected level of IPC in WFIRST, IPC increases the PSF\nsizes by $\\sim$5\\%. We present a linear fitting formula that describes the\nuncertainty in the PSF size or shape due to uncertainty in the IPC, which could\narise for example due to unknown time evolution of IPC as the detectors age or\ndue to spatial variation of IPC across the detector. We also study of the\neffect of a small anisotropy in the IPC, which further modifies the PSF shapes.\nOur results are a first, critical step in determining the hardware and\ncharacterization requirements for the detectors used in the WFIRST survey.", "positive": "Uncertainty Quantification of a Computer Model for Binary Black Hole\n Formation: In this paper, a fast and parallelizable method based on Gaussian Processes\n(GPs) is introduced to emulate computer models that simulate the formation of\nbinary black holes (BBHs) through the evolution of pairs of massive stars. Two\nobstacles that arise in this application are the a priori unknown conditions of\nBBH formation and the large scale of the simulation data. We address them by\nproposing a local emulator which combines a GP classifier and a GP regression\nmodel. The resulting emulator can also be utilized in planning future computer\nsimulations through a proposed criterion for sequential design. By propagating\nuncertainties of simulation input through the emulator, we are able to obtain\nthe distribution of BBH properties under the distribution of physical\nparameters." }, { "anchor": "Performance of the UVIT Level-2 Pipeline: Performance of the Level-2 pipeline, which translates the UVIT data created\nby the ISRO's ground segment processing systems (Level-1) into astronomer ready\nscientific data products, is described. This pipeline has evolved significantly\nfrom experiences during the in orbit mission. With time, the detector modules\nof UVIT developed certain defects which led to occasional corruption of imaging\nand timing data. This article will describe the improvements and mitigation\nplans incorporated in the pipeline and report its efficacy and quantify the\nperformance.", "positive": "Development of Superconducting On-chip Fourier Transform Spectrometers: Superconducting On-chip Fourier Transform Spectrometers (SOFTS) are\nbroadband, compact and electronic interferometers. Being extremely compact,\nSOFTS can fit into standard antenna coupled detector architectures. SOFTS will\nenable kilo-pixel spectro-imaging focal planes enhancing sub-millimeter\nscience; particularly cluster astrophysics / cosmology, CMB-science and line\nintensity mapping. This proceeding details the development, design and\nbench-marking of RF on-chip architecture of SOFTS for Ka and W bands." }, { "anchor": "Chandra Publication Statistics: In this study we develop and propose publication metrics, based on an\nanalysis of data from the Chandra bibliographic database, that are more\nmeaningful and less sensitive to observatory-specific characteristics than the\ntraditional metrics. They fall in three main categories: speed of publication;\nfraction of observing time published; and archival usage. Citation of results\nis a fourth category, but lends itself less well to definite statements. For\nChandra, the median time from observation to publication is 2.36 years; after\nabout 7 years 90% of the observing time is published; after 10 years 70% of the\nobserving time is published more than twice; and the total annual publication\noutput of the mission is 60-70% of the cumulative observing time available,\nassuming a two year lag between data retrieval and publication.", "positive": "Impact of Sodium Layer variations on the performance of the E-ELT MCAO\n module: Multi-Conjugate Adaptive Optics systems based on sodium Laser Guide Stars may\nexploit Natural Guide Stars to solve intrinsic limitations of artificial\nbeacons (tip-tilt indetermination and anisoplanatism) and to mitigate the\nimpact of the sodium layer structure and variability. The sodium layer may also\nhave transverse structures leading to differential effects among Laser Guide\nStars. Starting from the analysis of the input perturbations related to the\nSodium Layer variability, modeled directly on measured sodium layer profiles,\nwe analyze, through a simplified end-to-end simulation code, the impact of the\nlow/medium orders induced on global performance of the European Extremely Large\nTelescope Multi-Conjugate Adaptive Optics module MAORY." }, { "anchor": "A spectrograph instrument concept for the Prime Focus Spectrograph (PFS)\n on Subaru Telescope: We describe the conceptual design of the spectrograph opto-mechanical concept\nfor the SuMIRe Prime Focus Spectrograph (PFS) being developed for the SUBARU\ntelescope. The SuMIRe PFS will consist of four identical spectrographs, each\nreceiving 600 fibers from a 2400 fiber robotic positioner at the prime focus.\nEach spectrograph will have three channels covering in total, a wavelength\nrange from 380 nm to 1300 nm. The requirements for the instrument are\nsummarized in Section 1. We present the optical design and the optical\nperformance and analysis in Section 2. Section 3 introduces the mechanical\ndesign, its requirements and the proposed concepts. Finally, the AIT phases for\nthe Spectrograph System are described in Section 5.", "positive": "The e-MERLIN Data Reduction Pipeline: Written in Python and utilising ParselTongue to interface with the\nAstronomical Image Processing System (AIPS), the e-MERLIN data reduction\npipeline is intended to automate the procedures required in processing and\ncalibrating radio astronomy data from the e-MERLIN correlator. Driven by a\nplain text file of input parameters, the pipeline is modular and can be run in\nstages by the user, depending on requirements. The software includes options to\nload raw data, average in time and/or frequency, flag known sources of\ninterference, flag more comprehensively with SERPent, carry out some or all of\nthe calibration procedures including self-calibration), and image in either\nnormal or wide-field mode. It also optionally produces a number of useful\ndiagnostic plots at various stages so that the quality of the data can be\nassessed. The software is available for download from the e-MERLIN website or\nvia Github." }, { "anchor": "Deep Learning for space-variant deconvolution in galaxy surveys: Deconvolution of large survey images with millions of galaxies requires to\ndevelop a new generation of methods which can take into account a space variant\nPoint Spread Function (PSF) and have to be at the same time accurate and fast.\nWe investigate in this paper how Deep Learning (DL) could be used to perform\nthis task. We employ a U-Net Deep Neural Network (DNN) architecture to learn in\na supervised setting parameters adapted for galaxy image processing and study\ntwo strategies for deconvolution. The first approach is a post-processing of a\nmere Tikhonov deconvolution with closed form solution and the second one is an\niterative deconvolution framework based on the Alternating Direction Method of\nMultipliers (ADMM). Our numerical results based on GREAT3 simulations with\nrealistic galaxy images and PSFs show that our two approaches outperforms\nstandard techniques based on convex optimization, whether assessed in galaxy\nimage reconstruction or shape recovery. The approach based on Tikhonov\ndeconvolution leads to the most accurate results except for ellipticity errors\nat high signal to noise ratio where the ADMM approach performs slightly better,\nis also more computation-time efficient to process a large number of galaxies,\nand is therefore recommended in this scenario.", "positive": "FlashCam: a fully-digital camera for the medium-sized telescopes of the\n Cherenkov Telescope Array: The FlashCam group is currently preparing photomultiplier-tube based cameras\nproposed for the medium-sized telescopes (MST) of the Cherenkov Telescope Array\n(CTA). The cameras are designed around the FlashCam readout concept which is\nthe first fully-digital readout system for Cherenkov cameras, based on\ncommercial FADCs and FPGAs as key components for the front-end electronics\nmodules and a high performance camera server as back-end. This contribution\ndescribes the progress of the full-scale FlashCam camera prototype currently\nunder construction, as well as performance results also obtained with earlier\ndemonstrator setups. Plans towards the production and implementation of\nFlashCams on site are also briefly presented." }, { "anchor": "Selected astrometric catalogues: A selection of astrometric catalogues are presented in three tables for\nrespectively positions, proper motions and trigonometric parallaxes. The tables\ncontain characteristics of each catalogue showing the evolution in optical\nastrometry, in fact the evolution during the past 2000 years for positions. The\nnumber of stars and the accuracy are summarized by the weight of a catalogue,\nproportional with the number of stars and the statistical weight. The present\nreport originally from 2008 was revised in 2017 with much new information about\nthe accuracy of catalogues before 1800 AD. For the ongoing Gaia mission the\nwebsite and H{\\o}g (2017) may be consulted.", "positive": "Report of the Kavli IAU Workshop on Global Coordination: Future\n Space-Based Ultraviolet-Optical-Infrared Telescopes: International efforts play a key role in driving all areas of astrophysics.\nStrategic planning is essential to explore possible partnerships and joint\nprojects that otherwise could not be afforded, and to maximize their scientific\nreturn. For these reasons, the International Astronomical Union (IAU)\nestablished in 2016 the Working Group on Global Coordination of Ground and\nSpace Astrophysics. The Working Group held a Kavli IAU Workshop on \"Global\nCoordination: Future Space-Based Ultraviolet-Optical-Infrared Telescopes\" in\nJuly 2017, bringing together scientific leaders from 17 countries to discuss\ncompelling science drivers, technical requirements, political constraints, and\nopportunities for a future large-scale UV/optical/Infrared space mission. This\nreport summarizes the workshop and recommends that astronomers worldwide\nintensify their activities to explore the possibilities for science with such a\nmission, including consideration of instrumentation and technology definition\nand development, construction, launch, data analysis, and complementary\nscience. The workshop presentations are available at\nhttps://www.strw.leidenuniv.nl/KavliIAU2017." }, { "anchor": "SPH to Grid: a new integral conserving method: Analysing data from Smoothed Particle Hydrodynamics (SPH) simulations is\nabout understanding global fluid properties rather than individual fluid\nelements. Therefore, in order to properly understand the outcome of such\nsimulations it is crucial to transition from a particle to a grid based\npicture. In this paper we briefly summarise different methods of calculating a\nrepresentative volume discretisation from SPH data and propose an improved\nversion of commonly used techniques. We present a possibility to generate\naccurate 2D data directly without the CPU time and memory consuming detour over\na 3D grid. We lay out the importance of an accurate algorithm to conserve\nintegral fluid properties and to properly treat small scale structures using a\ntypical galaxy simulation snapshot. For demonstration purposes we additionally\ncalculate velocity power spectra and as expected find the main differences on\nsmall scales. Finally we propose two new multi-purpose analysis packages which\nutilise the new algorithms: Pygad and SPHMapper.", "positive": "A Digital Correlator Upgrade for the Arcminute MicroKelvin Imager: The Arcminute Microkelvin Imager (AMI) telescopes located at the Mullard\nRadio Astronomy Observatory near Cambridge have been significantly enhanced by\nthe implementation of a new digital correlator with 1.2 MHz spectral\nresolution. This system has replaced a 750-MHz resolution analogue lag-based\ncorrelator, and was designed to mitigate the effects of radio frequency\ninterference, particularly from geostationary satellites that contaminate\nobservations at low declinations. The upgraded instrument consists of 18 ROACH2\nField Programmable Gate Array platforms used to implement a pair of real-time\nFX correlators -- one for each of AMI's two arrays. The new system separates\nthe down-converted RF baseband signal from each AMI receiver into two 2.3\nGHz-wide sub-bands which are each digitized at 5-Gsps with 8 bits of precision.\nThese digital data streams are filtered into 2048 frequency channels and\ncross-correlated using FPGA hardware, with a commercial 10 Gb Ethernet switch\nproviding high-speed data interconnect. Images formed using data from the new\ndigital correlator show over an order of magnitude improvement in dynamic range\nover the previous system. The ability to observe at low declinations has also\nbeen significantly improved." }, { "anchor": "A pointing solution for the medium size telescopes for the Cherenkov\n Telescope Array: The pointing capability of a telescope in the Cherenkov Telescope Array (CTA)\nis a crucial aspect in the calibration of the instrument. It describes how a\nposition in the sky is transformed to the focal plane of the telescope and\nallows precise directional reconstructions of atmospheric particle showers. The\nfavoured approach for pointing calibrations of the Medium Size Telescopes (MST)\nis the utilisation of an CCD-camera installed in the centre of the dish, which\nimages the night sky and the focal plane simultaneously. The technical\nimplementation of this solution and test results taken over a period of one\nyear at the MST prototype in Berlin/Adlershof are presented. Investigations of\npointing calibration precision with simulated data and real data taken during\ntest runs of the prototype telescope will also be shown.", "positive": "Spectral Calibration of the Fluorescence Telescopes of the Pierre Auger\n Observatory: We present a novel method to measure precisely the relative spectral response\nof the fluorescence telescopes of the Pierre Auger Observatory. We used a\nportable light source based on a xenon flasher and a monochromator to measure\nthe relative spectral efficiencies of eight telescopes in steps of 5 nm from\n280 nm to 440 nm. Each point in a scan had approximately 2 nm FWHM out of the\nmonochromator. Different sets of telescopes in the observatory have different\noptical components, and the eight telescopes measured represent two each of the\nfour combinations of components represented in the observatory. We made an\nend-to-end measurement of the response from different combinations of optical\ncomponents, and the monochromator setup allowed for more precise and complete\nmeasurements than our previous multi-wavelength calibrations. We find an\noverall uncertainty in the calibration of the spectral response of most of the\ntelescopes of 1.5% for all wavelengths; the six oldest telescopes have larger\noverall uncertainties of about 2.2%. We also report changes in physics\nmeasureables due to the change in calibration, which are generally small." }, { "anchor": "The Athena++ Adaptive Mesh Refinement Framework: Multigrid Solvers for\n Self-Gravity: We describe the implementation of multigrid solvers in the Athena++ adaptive\nmesh refinement (AMR) framework and their application to the solution of the\nPoisson equation for self-gravity. The new solvers are built on top of the AMR\nhierarchy and TaskList framework of Athena++ for efficient parallelization. We\nadopt a conservative formulation for the Laplacian operator that avoids\nartificial accelerations at level boundaries. Periodic, fixed, and\nzero-gradient boundary conditions are implemented, as well as open boundary\nconditions based on a multipole expansion. Hybrid parallelization using both\nMPI and OpenMP is adopted, and we present results of tests demonstrating the\naccuracy and scaling of the methods. On a uniform grid we show multigrid\nsignificantly outperforms methods based on FFTs, and requires only a small\nfraction of the compute time required by the (highly optimized)\nmagnetohydrodynamic solver in Athena++. As a demonstration of the capabilities\nof the methods, we present the results of a test calculation of magnetized\nprotostellar collapse on an adaptive mesh.", "positive": "A Vigorous Explorer Program: Explorers have made breakthroughs in many fields of astrophysics. The science\nfrom both these missions contributed to three Nobel Prizes - Giacconi (2002),\nMather, and Smoot (2006). Explorers have: marked the definitive beginning of\nprecision cosmology, discovered that short gamma-ray bursts are caused by\ncompact star mergers and have measured metalicity to redshifts z>6. NASA\nExplorers do cutting-edge science that cannot be done by facility-class\ninstruments. The Explorer program provides a rapid response to changing science\nand technology, to enable cutting-edge science at moderate cost. Explorers also\nenable innovation, and engage & train scientists, managers and engineers,\nadding human capital to NASA and the nation. The astrophysics Explorer launch\nrate now being achieved is 1 per 3 years, and budget projections are in the\n$150M/year range for the next five years. A newly Vigorous Explorer Program\nshould be created to: 1. Reach the long-stated goal of annual astrophysics\nlaunches; 2. Find additional launch options for Explorers and actively\nencourage cost savings in launchers and spacecraft, such as new commercial\nvehicles and innovative partnerships. 3. Mitigate risk via stronger technical\ndevelopment and sub-orbital programs, and through longer, more thorough, Phase\nA programs, potentially reducing the need for a 30% contingency; 4. Strive to\nprotect the funding for missions that have reached Phase B, to prevent\nsignificant launch slips and cancellations, with a goal of 4 to 5 years from\nPhase B to launch; 5. Review the project management procedures and requirements\nto seek cost reductions, including the risk management strategy and the review\nand reporting process; 6. Review and possibly modify the cost caps for all\nExplorer classes to optimize scientific returns per dollar. [ABRIDGED]" }, { "anchor": "Preliminary design of the Visible Spectro-Polarimeter for the Advanced\n Technology Solar Telescope: The Visible Spectro-Polarimeter (ViSP) is one of the first light instruments\nfor the Advanced Technology Solar Telescope (ATST). It is an echelle\nspectrograph designed to measure three different regions of the solar spectrum\nin three separate focal planes simultaneously between 380 and 900 nm. It will\nuse the polarimetric capabilities of the ATST to measure the full Stokes\nparameters across the line profiles. By measuring the polarization in\nmagnetically sensitive spectral lines the magnetic field vector as a function\nof height in the solar atmosphere can be obtained, along with the associated\nvariation of the thermodynamic properties. The ViSP will have a spatial\nresolution of 0.04 arcsec over a 2 arcmin field of view (at 600 nm). The\nminimum spectral resolving power for all the focal planes is 180,000. The\nspectrograph supports up to 4 diffraction gratings and is fully automated to\nallow for rapid reconfiguration.", "positive": "Optimal stellar photometry for multi-conjugate adaptive optics systems\n using science-based metrics: We present a detailed discussion of how to obtain precise stellar photometry\nin crowded fields using images from multi-conjugate adaptive optics (MCAO)\nsystems, with the intent of informing the scientific development of this key\ntechnology for the Extremely Large Telescopes. We use deep J and K_s exposures\nof NGC 1851 taken with the Gemini Multi-Conjugate Adaptive Optics System (GeMS)\non Gemini South to quantify the performance of the instrument and to develop an\noptimal strategy for stellar photometry using PSF-fitting techniques. We judge\nthe success of the various methods we employ by using science-based metrics,\nparticularly the width of the main sequence turn-off region. We also compare\nthe GeMS photometry with the exquisite HST data in the visible of the same\ntarget. We show that the PSF produced by GeMS possesses significant spatial and\ntemporal variability that must be accounted for during the analysis. We show\nthat the majority of the variation of the PSF occurs within the \"control\nradius\" of the MCAO system and that the best photometry is obtained when the\nPSF radius is chosen to closely match this spatial scale. We identify\nphotometric calibration as a critical issue for next generation MCAO systems\nsuch as those on TMT and E-ELT. Our final CMDs reach K_s~22---below the main\nsequence knee---making it one of the deepest for a globular cluster available\nfrom the ground. Theoretical isochrones are in remarkable agreement with the\nstellar locus in our data from below the main sequence knee to the upper red\ngiant branch." }, { "anchor": "Multi-frequency image reconstruction for radio interferometry. A\n regularized inverse problem approach: We describe a \"spatio-spectral\" deconvolution algorithm for wide-band imaging\nin radio interferometry. In contrast with the existing multi-frequency\nreconstruction algorithms, the proposed method does not rely on a model of the\nsky-brightness spectral distribution. This non-parametric approach can be of\nparticular interest for the new generation of low frequency radiotelescopes.\nThe proposed solution formalizes the reconstruction problem as a convex\noptimization problem with spatial and spectral regularizations. The efficiency\nof this approach has been already proven for narrow-band image reconstruction\nand the present contribution can be considered as its extension to the\nmulti-frequency case. Because the number of frequency bands multiplies the size\nof the inverse problem, particular attention is devoted to the derivation of an\niterative large scale optimization algorithm. It is shown that the main\ncomputational bottleneck of the approach, which lies in the resolution of a\nlinear system, can be efficiently overcome by a fully parallel implementation\nw.r.t. the frequencies, where each processor reconstructs a narrow-band image.\nAll the other optimization steps are extremely fast. A parallel implementation\nof the algorithm in Julia is publicly available at\nhttps://github.com/andferrari. Preliminary simulations illustrate the\nperformances of the method and its ability to reconstruct complex\nspatio-spectral structures.", "positive": "Optimizing optical follow-up of gravitational-wave candidates: Observations with interferometric gravitational-wave detectors result in\nprobability sky maps that are multimodal and spread over 10-100 deg^2. We\npresent a scheme for maximizing the probability of imaging optical counterparts\nto gravitational-wave transients given limited observing resources. Our\nframework is capable of coordinating many telescopes with different fields of\nview and limiting magnitudes. We present a case study comparing three different\nplanning algorithms. We find that, with the network of telescopes that was used\nin the most recent joint LIGO-Virgo science run, a relatively straightforward\ncoordinated approach doubles the detection efficiency relative to each\ntelescope observing independently." }, { "anchor": "Does light from steady sources bear any observable imprint of the\n dispersive intergalactic medium?: There has recently been some interest in the prospect of detecting ionized\nintergalactic baryons by examining the properties of incoherent light from\nbackground cosmological sources, namely quasars. Although the paper by\n\\cite{lieu13} proposed a way forward, it was refuted by the later theoretical\nwork of \\cite{hir14} and observational study of \\cite{hal16}. In this paper we\ninvestigated in detail the manner in which incoherent radiation passes through\na dispersive medium both from the frameworks of classical and quantum\nelectrodynamics, which led us to conclude that the premise of \\cite{lieu13}\nwould only work if the pulses involved are genuinely classical ones involving\nmany photons per pulse, but unfortunately each photon must not be treated as a\npulse that is susceptible to dispersive broadening. We are nevertheless able to\nchange the tone of the paper at this juncture, by pointing out that because\ncurrent technology allows one to measure the phase of individual modes of radio\nwaves from a distant source, the most reliable way of obtaining irrefutable\nevidence of dispersion, namely via the detection of its unique signature of a\nquadratic spectral phase, may well be already accessible. We demonstrate how\nthis technique is only applied to measure the column density of the ionized\nintergalactic medium.", "positive": "A near infrared frequency comb for Y+J band astronomical spectroscopy: Radial velocity (RV) surveys supported by high precision wavelength\nreferences (notably ThAr lamps and I2 cells) have successfully identified\nhundreds of exoplanets; however, as the search for exoplanets moves to cooler,\nlower mass stars, the optimum wave band for observation for these objects moves\ninto the near infrared (NIR) and new wavelength standards are required. To\naddress this need we are following up our successful deployment of an H\nband(1.45-1.7{\\mu}m) laser frequency comb based wavelength reference with a\ncomb working in the Y and J bands (0.98-1.3{\\mu}m). This comb will be optimized\nfor use with a 50,000 resolution NIR spectrograph such as the Penn State\nHabitable Zone Planet Finder. We present design and performance details of the\ncurrent Y+J band comb." }, { "anchor": "Verification of the Optical System of the 9.7-m Prototype\n Schwarzschild-Couder Telescope: For the first time in the history of ground-based $\\gamma$-ray astronomy, the\non-axis performance of the dual mirror, aspheric, aplanatic\nSchwarzschild-Couder optical system has been demonstrated in a $9.7$-m aperture\nimaging atmospheric Cherenkov telescope. The novel design of the prototype\nSchwarzschild-Couder Telescope (pSCT) is motivated by the need of the\nnext-generation Cherenkov Telescope Array (CTA) observatory to have the ability\nto perform wide ($\\geq 8^{\\circ}$) field-of-view observations simultaneously\nwith superior imaging of atmospheric cascades (resolution of $0.067^{\\circ}$\nper pixel or better). The pSCT design, if implemented in the CTA installation,\nhas the potential to improve significantly both the $\\gamma$-ray angular\nresolution and the off-axis sensitivity of the observatory, reaching nearly the\ntheoretical limit of the technique and thereby making a major impact on the CTA\nobservatory sky survey programs, follow-up observations of multi-messenger\ntransients with poorly known initial localization, as well as on the spatially\nresolved spectroscopic studies of extended $\\gamma$-ray sources. This\ncontribution reports on the initial alignment procedures and\npoint-spread-function results for the challenging segmented aspheric primary\nand secondary mirrors of the pSCT.", "positive": "Performance characterization and near-realtime monitoring of MUSE\n adaptive optics modes at Paranal: The Multi Unit Spectroscopic Explorer (MUSE) is an integral field\nspectrograph on the Very Large Telescope Unit Telescope 4, capable of laser\nguide star assisted and tomographic adaptive optics using the GALACSI module.\nIts observing capabilities include a wide field (1 square arcmin), ground layer\nAO mode (WFM-AO) and a narrow field (7.5\"x7.5\"), laser tomography AO mode\n(NFM-AO). The latter has had several upgrades in the 4 years since\ncommissioning, including an optimisation of the control matrices for the AO\nsystem and a new sub-electron noise detector for its infra-red low order\nwavefront sensor. We set out to quantify the NFM-AO system performance by\nanalysing $\\sim$230 spectrophotometric standard star observations taken over\nthe last 3 years. To this end we expand upon previous work, designed to\nfacilitate analysis of the WFM-AO system performance. We briefly describe the\nframework that will provide a user friendly, semi-automated way for system\nperformance monitoring during science operations. We provide the results of our\nperformance analysis, chiefly through the measured Strehl ratio and full width\nat half maximum (FWHM) of the core of the point spread function (PSF) using two\nPSF models, and correlations with atmospheric conditions. These results will\nfeed into a range of applications, including providing a more accurate\nprediction of the system performance as implemented in the exposure time\ncalculator, and the associated optimization of the scientific output for a\ngiven set of limiting atmospheric conditions." }, { "anchor": "The Simons Observatory: Cryogenic Half Wave Plate Rotation Mechanism for\n the Small Aperture Telescopes: We present the requirements, design and evaluation of the cryogenic\ncontinuously rotating half-wave plate (CHWP) for the Simons Observatory (SO).\nSO is a cosmic microwave background (CMB) polarization experiment at Parque\nAstron\\'{o}mico Atacama in northern Chile that covers a wide range of angular\nscales using both small (0.42 m) and large (6 m) aperture telescopes. In\nparticular, the small aperture telescopes (SATs) focus on large angular scales\nfor primordial B-mode polarization. To this end, the SATs employ a CHWP to\nmodulate the polarization of the incident light at 8~Hz, suppressing\natmospheric $1/f$ noise and mitigating systematic uncertainties that would\notherwise arise due to the differential response of detectors sensitive to\northogonal polarizations. The CHWP consists of a 505 mm diameter achromatic\nsapphire HWP and a cryogenic rotation mechanism, both of which are cooled down\nto $\\sim$50 K to reduce detector thermal loading. Under normal operation the\nHWP is suspended by a superconducting magnetic bearing and rotates with a\nconstant 2 Hz frequency, controlled by an electromagnetic synchronous motor.\nThe rotation angle is detected through an angular encoder with a noise level of\n0.07$\\mu\\mathrm{rad}\\sqrt{\\mathrm{s}}$. During a cooldown, the rotor is held in\nplace by a grip-and-release mechanism that serves as both an alignment device\nand a thermal path. In this paper we provide an overview of the SO SAT CHWP:\nits requirements, hardware design, and laboratory performance.", "positive": "Feature importance for machine learning redshifts applied to SDSS\n galaxies: We present an analysis of importance feature selection applied to photometric\nredshift estimation using the machine learning architecture Decision Trees with\nthe ensemble learning routine Adaboost (hereafter RDF). We select a list of 85\neasily measured (or derived) photometric quantities (or `features') and\nspectroscopic redshifts for almost two million galaxies from the Sloan Digital\nSky Survey Data Release 10. After identifying which features have the most\npredictive power, we use standard artificial Neural Networks (aNN) to show that\nthe addition of these features, in combination with the standard magnitudes and\ncolours, improves the machine learning redshift estimate by 18% and decreases\nthe catastrophic outlier rate by 32%. We further compare the redshift estimate\nusing RDF with those from two different aNNs, and with photometric redshifts\navailable from the SDSS. We find that the RDF requires orders of magnitude less\ncomputation time than the aNNs to obtain a machine learning redshift while\nreducing both the catastrophic outlier rate by up to 43%, and the redshift\nerror by up to 25%. When compared to the SDSS photometric redshifts, the RDF\nmachine learning redshifts both decreases the standard deviation of residuals\nscaled by 1/(1+z) by 36% from 0.066 to 0.041, and decreases the fraction of\ncatastrophic outliers by 57% from 2.32% to 0.99%." }, { "anchor": "FOXSI-2: Upgrades of the Focusing Optics X-ray Solar Imager for its\n Second Flight: The Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket payload flew\nfor the second time on 2014 December 11. To enable direct Hard X-Ray (HXR)\nimaging spectroscopy, FOXSI makes use of grazing-incidence replicated focusing\noptics combined with fine-pitch solid-state detectors. FOXSI's first flight\nprovided the first HXR focused images of the Sun. For FOXSI's second flight\nseveral updates were made to the instrument including updating the optics and\ndetectors as well as adding a new Solar Aspect and Alignment System (SAAS).\nThis paper provides an overview of these updates as well as a discussion of\ntheir measured performance.", "positive": "ARWV Code User Manual: With this report we provide users of an easy manual to facilitate the proper\ndownload and use of a sophisticated, high precision, few-body code originally\ndeveloped by S. Mikkola, and later largely improved and implemented to treat a\nvariety of cases. The code download can be done via the link\nhttps://drive.google.com/file/d/16FkVVR4Tk8eKhKMju2vQ9rlWI4Mpv01W/view\n The use of the code is free upon proper citation. The work is in progress and\nusers are invited to help the authors to improve both the code and the user\nhandbook." }, { "anchor": "RAPOC : the Rosseland and Planck opacity converter. A user-friendly and\n fast opacity program for Python: RAPOC (Rosseland and Planck Opacity Converter) is a Python 3 code that\ncalculates Rosseland and Planck mean opacities (RPMs) from wavelength-dependent\nopacities for a given temperature, pressure, and wavelength range. In addition\nto being user-friendly and rapid, RAPOC can interpolate between discrete data\npoints, making it flexible and widely applicable to the astrophysical and\nEarth-sciences fields, as well as in engineering. For the input data, RAPOC can\nuse ExoMol and DACE data, or any user-defined data, provided that it is in a\nreadable format. In this paper, we present the RAPOC code and compare its\ncalculated Rosseland and Planck mean opacities with other values found in the\nliterature. The RAPOC code is open-source and available on Pypi and GitHub.", "positive": "Reference image selection for difference imaging analysis: Difference image analysis (DIA) is an effective technique for obtaining\nphotometry in crowded fields, relative to a chosen reference image. As yet,\nhowever, optimal reference image selection is an unsolved problem. We examine\nhow this selection depends on the combination of seeing, background and\ndetector pixel size. Our tests use a combination of simulated data and quality\nindicators from DIA of well-sampled optical data and under-sampled\nnear-infrared data from the OGLE and VVV surveys, respectively. We search for a\nfigure-of-merit (FoM) which could be used to select reference images for each\nsurvey. While we do not find a universally applicable FoM, survey-specific\nmeasures indicate that the effect of spatial under-sampling may require a\nchange in strategy from the standard DIA approach, even though seeing remains\nthe primary criterion. We find that background is not an important criterion\nfor reference selection, at least for the dynamic range in the images we test.\nFor our analysis of VVV data in particular, we find that spatial under-sampling\nis best handled by reversing the standard DIA procedure and convolving target\nimages to a better-sampled (poor seeing) reference image." }, { "anchor": "Re-testing the JET-X Flight Module No. 2 at the PANTER facility: The Joint European X-ray Telescope (JET-X) was the core instrument of the\nRussian Spectrum-X-gamma space observatory. It consisted of two identical soft\nX-ray (0.3 - 10 keV) telescopes with focusing optical modules having a measured\nangular resolution of nearly 15 arcsec. Soon after the payload completion, the\nmission was cancelled and the two optical flight modules (FM) were brought to\nthe Brera Astronomical Observatory where they had been manufactured. After 16\nyears of storage, we have utilized the JET-X FM2 to test at the PANTER X-ray\nfacility a prototype of a novel X-ray polarimetric telescope, using a Gas Pixel\nDetector (GPD) with polarimetric capabilities in the focal plane of the FM2.\nThe GPD was developed by a collaboration between INFN-Pisa and INAF-IAPS. In\nthe first phase of the test campaign, we have re-tested the FM2 at PANTER to\nhave an up-to-date characterization in terms of angular resolution and\neffective area, while in the second part of the test the GPD has been placed in\nthe focal plane of the FM2. In this paper we report the results of the tests of\nthe sole FM2, using an unpolarized X-ray source, comparing the results with the\ncalibration done in 1996.", "positive": "Fireball streak detection with minimal CPU processing requirements for\n the Desert Fireball Network data processing pipeline: The detection of fireballs streaks in astronomical imagery can be carried out\nby a variety of methods. The Desert Fireball Network--DFN--uses a network of\ncameras to track and triangulate incoming fireballs to recover meteorites with\norbits. Fireball detection is done on-camera, but due to the design constraints\nimposed by remote deployment, the cameras are limited in processing power and\ntime. We describe the processing software used for fireball detection under\nthese constrained circumstances. A cascading approach was implemented, whereby\ncomputationally simple filters are used to discard uninteresting portions of\nthe images, allowing for more computationally expensive analysis of the\nremainder. This allows a full night's worth of data; over 1000 36 megapixel\nimages to be processed each day using a low power single board computer. The\nalgorithms chosen give a single camera successful detection large fireball rate\nof better than 96 percent, when compared to manual inspection, although\nsignificant numbers of false positives are generated. The overall network\ndetection rate for triangulated large fireballs is estimated to be better than\n99.8 percent, by ensuring that there are multiple double stations chances to\ndetect one fireball." }, { "anchor": "Flux Calibration of Broadband Far Infrared and Submillimetre Photometric\n Instruments: Theory and Application to Herschel-SPIRE: Photometric instruments operating at far infrared to millimetre wavelengths\noften have broad spectral passbands (central wavelength/bandwidth ~ 3 or less),\nespecially those operating in space. A broad passband can result in significant\nvariation of the beam profile and aperture efficiency across the passband,\neffects which thus far have not generally been taken into account in the flux\ncalibration of such instruments. With absolute calibration uncertainties\nassociated with the brightness of primary calibration standards now in the\nregion of 5% or less, variation of the beam properties across the passband can\nbe a significant contributor to the overall calibration accuracy for extended\nemission. We present a calibration framework which takes such variations into\naccount for both antenna-coupled and absorber-coupled focal plane\narchitectures. The scheme covers point source and extended source cases, and\nalso the intermediate case of a semi-extended source profile. We apply the new\nmethod to the Herschel-SPIRE space-borne photometer.", "positive": "Estimating effective wind speed from Gemini Planet Imager's adaptive\n optics data using covariance maps: The Earth's turbulent atmosphere results in speckled and blurred images of\nastronomical objects when observed by ground based visible and near-infrared\ntelescopes. Adaptive optics (AO) systems are employed to reduce these\natmospheric effects by using wavefront sensors (WFS) and deformable mirrors.\nSome AO systems are not fast enough to correct for strong, fast, high\nturbulence wind layers leading to the wind butterfly effect, or wind-driven\nhalo, reducing contrast capabilities in coronagraphic images. Estimating the\neffective wind speed of the atmosphere allows us to calculate the atmospheric\ncoherence time. This is not only an important parameter to understand for site\ncharacterization but could be used to help remove the wind butterfly in post\nprocessing. Here we present a method for estimating the atmospheric effective\nwind speed from spatio-temporal covariance maps generated from pseudo open-loop\n(POL) WFS data. POL WFS data is used as it aims to reconstruct the full\nwavefront information when operating in closed-loop. The covariance maps show\nhow different atmospheric turbulent layers traverse the telescope. Our method\nsuccessfully recovered the effective wind speed from simulated WFS data\ngenerated with the soapy python library. The simulated atmospheric turbulence\nprofiles consist of two turbulent layers of ranging strengths and velocities.\nThe method has also been applied to Gemini Planet Imager (GPI) AO WFS data.\nThis gives insight into how the effective wind speed can affect the wind-driven\nhalo seen in the AO image point spread function. In this paper, we will present\nresults from simulated and GPI WFS data." }, { "anchor": "GAVIP: A Platform for Gaia Data Analysis: Gaia is a major European Space Agency (ESA) astrophysics mission designed to\nmap and analyse 10$^9$ stars, ultimately generating more than 1 PetaByte of\ndata products. As Gaia data becomes publicly available and reaches a wider\naudience, there is an increasing need to facilitate the further use of Gaia\nproducts without needing to download large datasets. The Gaia Added Value\nInterface Platform (GAVIP) is designed to address this challenge by providing\nan innovative platform within which scientists can submit and deploy code,\npackaged as \"Added Value Interfaces\" (AVIs), which will be executed close to\nthe data. Deployed AVIs and associated outputs may also be made available to\nother GAVIP platform users, thus providing a mechanism for scientific\nexperiment reproducibility. This paper describes the capabilities and features\nof GAVIP.", "positive": "IGRINS Slit-Viewing Camera Software: We have developed observation control software for the Immersion GRating\nINfrared Spectrometer (IGRINS) slit-viewing camera module, which maintains the\nposition of an astronomical target on the spectroscopic slit. It is composed of\nseveral packages that monitor and control the system, acquire the images, and\ncompensate for the tracking error by sending tracking feedback information to\nthe telescope control system. For efficient development and maintenance of each\nsoftware package, we have applied software engineering methods, i.e., a spiral\nsoftware development with model-based design. It is not trivial to define the\nshape and center of astronomical object point spread functions (PSFs), which do\nnot have symmetric Gaussian profiles in short exposure (<4 s) guiding images.\nEfforts to determine the PSF centroid are additionally complicated by the core\nsaturation of bright guide stars. We have applied both a two-dimensional\nGaussian fitting algorithm (2DGA) and center balancing algorithm (CBA) to\nidentify an appropriate method for IGRINS in the near-infrared K-band. The CBA\nderives the expected center position along the slit-width by referencing the\nspillover flux ratio of the PSF wings on both sides of the slit. In this\nresearch, we have compared the accuracy and reliability of the CBA to the 2DGA\nby using data from IGRINS commissioning observations at McDonald Observatory.\nWe find that the performance of each algorithm depends on the brightness of the\ntargets and the seeing conditions, with the CBA performing better in typical\nobserving scenarios. The algorithms and test results we present can be utilized\nwith future spectroscopic slit observations in various observing conditions and\nfor a variety of spectrograph designs." }, { "anchor": "Direction Dependent Effects In Wide-Field Wideband Full Stokes Radio\n Imaging: Synthesis imaging in radio astronomy is affected by instrumental and\natmospheric effects which introduce direction-dependent (DD) gains.The antenna\npower pattern varies both as a function of time and frequency. The broad band\ntime varying nature of the antenna power pattern when not corrected leads to\ngross errors in full Stokes imaging and flux estimation. In this poster we\nexplore the errors that arise in image deconvolution while not accounting for\nthe time and frequency dependence of the antenna power pattern. Simulations\nwere conducted with the wide-band full Stokes power pattern of the Karl G.\nJansky Very Large Array (VLA) antennas to demonstrate the level of errors\narising from direction-dependent gains and their non-neglegible impact on\nupcoming sky surveys such as the VLASS. DD corrections through hybrid\nprojection algorithms are computationally expensive to perform. A highly\nparallel implementation through high performance computing architectures is the\nonly feasible way of applying these corrections to the large data sizes of\nthese upcoming surveys.", "positive": "The small size telescope projects for the Cherenkov Telescope Array: The small size telescopes (SSTs), spread over an area of several square km,\ndominate the CTA sensitivity in the photon energy range from a few TeV to over\n100 TeV, enabling for the detailed exploration of the very high energy\ngamma-ray sky. The proposed telescopes are innovative designs providing a wide\nfield of view. Two of them, the ASTRI (Astrophysics con Specchi a Tecnologia\nReplicante Italiana) and the GCT (Gamma-ray Cherenkov Telescope) telescopes,\nare based on dual mirror Schwarzschild-Couder optics, with primary mirror\ndiameters of 4 m. The third, SST-1M, is a Davies-Cotton design with a 4 m\ndiameter mirror. Progress with the construction and testing of prototypes of\nthese telescopes is presented. The SST cameras use silicon photomultipliers,\nwith preamplifier and readout/trigger electronics designed to optimize the\nperformance of these sensors for (atmospheric) Cherenkov light. The status of\nthe camera developments is discussed. The SST sub-array will consist of about\n70 telescopes at the CTA southern site. Current plans for the implementation of\nthe array are presented." }, { "anchor": "Deep learning with photosensor timing information as a background\n rejection method for the Cherenkov Telescope Array: New deep learning techniques present promising new analysis methods for\nImaging Atmospheric Cherenkov Telescopes (IACTs) such as the upcoming Cherenkov\nTelescope Array (CTA). In particular, the use of Convolutional Neural Networks\n(CNNs) could provide a direct event classification method that uses the entire\ninformation contained within the Cherenkov shower image, bypassing the need to\nHillas parameterise the image and allowing fast processing of the data.\n Existing work in this field has utilised images of the integrated charge from\nIACT camera photomultipliers, however the majority of current and upcoming\ngeneration IACT cameras have the capacity to read out the entire photosensor\nwaveform following a trigger. As the arrival times of Cherenkov photons from\nExtensive Air Showers (EAS) at the camera plane are dependent upon the altitude\nof their emission and the impact distance from the telescope, these waveforms\ncontain information potentially useful for IACT event classification.\n In this test-of-concept simulation study, we investigate the potential for\nusing these camera pixel waveforms with new deep learning techniques as a\nbackground rejection method, against both proton and electron induced EAS. We\nfind that a means of utilising their information is to create a set of seven\nadditional 2-dimensional pixel maps of waveform parameters, to be fed into the\nmachine learning algorithm along with the integrated charge image. Whilst we\nultimately find that the only classification power against electrons is based\nupon event direction, methods based upon timing information appear to\nout-perform similar charge based methods for gamma/hadron separation. We also\nreview existing methods of event classifications using a combination of deep\nlearning and timing information in other astroparticle physics experiments.", "positive": "GONG third generation camera: Detector selection and feasibility study: Aging GONG second generation cameras (Silicon Mountain Design(TM) cameras)\nwere planned to be replaced after their long service of more than a decade.\nThis prompted a market-wide search for a potential replacement detector to meet\nthe GONG science requirements. This report provides some history of the search\nprocess, a comparison between CMOS and CCD type sensors and then a quantitative\nevaluation of potential candidates to arrive at final selection. Further, a\nfeasibility study of the selected sensor for adaptation to GONG optical system\nwas done and sensor characteristics were independently verified in the\nlaboratory. This technical report gives description of these studies and tests." }, { "anchor": "Normal Metal Hot-Electron Nanobolometer with Johnson Noise Thermometry\n Readout: The sensitivity of a THz hot-electron nanobolometer (nano-HEB) made from a\nnormal metal is analyzed. Johnson Noise Thermometry (JNT) is employed as a\nreadout technique. In contrast to its superconducting TES counterpart, the\nnormal-metal nano-HEB can operate at any cryogenic temperature depending on the\nrequired radiation background limited Noise Equivalent Power (NEP). It does not\nrequire bias lines; 100s of nano-HEBs can be read by a single low-noise X-band\namplifier via a filter bank channelizer. The modeling predicts that even with\nthe sensitivity penalty due to the amplifier noise, an NEP ~ 10$^{-20}$ -\n10$^{-19}$ W/Hz$^{1/2}$ can be expected at 50-100 mK in 10-20 nm thin titanium\n(Ti) normal metal HEBs with niobium (Nb) contacts. This NEP is fairly constant\nover a range of readout frequencies ~ 10 GHz. Although materials with weaker\nelectron-phonon coupling (bismuth, graphene) do not improve the minimum\nachievable NEP, they can be considered if a larger than 10 GHz readout\nbandwidth is required.", "positive": "4GREAT -- a four-color receiver for high-resolution airborne terahertz\n spectroscopy: 4GREAT is an extension of the German Receiver for Astronomy at Terahertz\nfrequencies (GREAT) operated aboard the Stratospheric Observatory for Infrared\nAstronomy (SOFIA). The spectrometer comprises four different detector bands and\ntheir associated subsystems for simultaneous and fully independent science\noperation. All detector beams are co-aligned on the sky. The frequency bands of\n4GREAT cover 491-635, 890-1090, 1240-1525 and 2490-2590 GHz, respectively. This\npaper presents the design and characterization of the instrument, and its\nin-flight performance. 4GREAT saw first light in June 2018, and has been\noffered to the interested SOFIA communities starting with observing cycle 6." }, { "anchor": "Time Domain Astronomy with the THESEUS Satellite: THESEUS is a medium size space mission of the European Space Agency,\ncurrently under evaluation for a possible launch in 2032. Its main objectives\nare to investigate the early Universe through the observation of gamma-ray\nbursts and to study the gravitational waves electromagnetic counterparts and\nneutrino events. On the other hand, its instruments, which include a wide field\nof view X-ray (0.3-5 keV) telescope based on lobster-eye focusing optics and a\ngamma-ray spectrometer with imaging capabilities in the 2-150 keV range, are\nalso ideal for carrying out unprecedented studies in time domain astrophysics.\nIn addition, the presence onboard of a 70 cm near infrared telescope will allow\nsimultaneous multi-wavelegth studies. Here we present the THESEUS capabilities\nfor studying the time variability of different classes of sources in parallel\nto, and without affecting, the gamma-ray bursts hunt.", "positive": "A method to localize gamma-ray bursts using POLAR: The hard X-ray polarimeter POLAR aims to measure the linear polarization of\nthe 50-500 keV photons arriving from the prompt emission of gamma-ray bursts\n(GRBs). The position in the sky of the detected GRBs is needed to determine\ntheir level of polarization. We present here a method by which, despite of the\npolarimeter incapability of taking images, GRBs can be roughly localized using\nPOLAR alone. For this purpose scalers are attached to the output of the 25\nmulti-anode photomultipliers (MAPMs) that collect the light from the POLAR\nscintillator target. Each scaler measures how many GRB photons produce at least\none energy deposition above 50 keV in the corresponding MAPM. Simulations show\nthat the relative outputs of the 25 scalers depend on the GRB position. A\ndatabase of very strong GRBs simulated at 10201 positions has been produced.\nWhen a GRB is detected, its location is calculated searching the minimum of the\nchi2 obtained in the comparison between the measured scaler pattern and the\ndatabase. This GRB localization technique brings enough accuracy so that the\nerror transmitted to the 100% modulation factor is kept below 10% for GRBs with\nfluence Ftot \\geq 10^(-5) erg cm^(-2) . The POLAR localization capability will\nbe useful for those cases where no other instruments are simultaneously\nobserving the same field of view." }, { "anchor": "Numerical modelling of the proposed WFIRST-AFTA coronagraphs and their\n predicted optical performances: The WFIRST-AFTA 2.4 m telescope will provide in the next decade the\nopportunity to host a coronagraph for the imaging and spectroscopy of planets\nand disks. The telescope, however, is not ideal, given its obscured aperture.\nOnly recently have coronagraph designs been thoroughly investigated that can\nefficiently work with this configuration. Three coronagraph designs, the hybrid\nLyot, the shaped pupil, and the phase-induced amplitude-apodization complex\nmask coronagraph (PIAA-CMC) have been selected for further development by the\nAFTA project. Real-world testbed demonstrations of these have just begun, so\nfor now the most reliable means of evaluating their potential performance comes\nfrom numerical modeling incorporating diffraction propagation, realistic system\nmodels, and simulated wavefront sensing and control. Here we present the\nmethods of performance evaluation and results for the current coronagraph\ndesigns.", "positive": "Testing of General Relativity with Geodetic VLBI: The geodetic VLBI technique is capable of measuring the Sun's gravity light\ndeflection from distant radio sources around the whole sky. This light\ndeflection is equivalent to the conventional gravitational delay used for the\nreduction of geodetic VLBI data. While numerous tests based on a global set of\nVLBI data have shown that the parameter 'gamma' of the post-Newtonian\napproximation is equal to unity with a precision of about 0.02 percent, more\ndetailed analysis reveals some systematic deviations depending on the angular\nelongation from the Sun. In this paper a limited set of VLBI observations near\nthe Sun were adjusted to obtain the estimate of the parameter 'gamma' free of\nthe elongation angle impact. The parameter 'gamma' is still found to be close\nto unity with precision of 0.06 percent, two subsets of VLBI data measured at\nshort and long baselines produce some statistical inconsistency." }, { "anchor": "Performance Analysis of GPU-Accelerated Filter-Based Source Finding for\n HI Spectral Line Image Data: Searching for sources of electromagnetic emission in spectral-line radio\nastronomy interferometric data is a computationally intensive process. Parallel\nprogramming techniques and High Performance Computing hardware may be used to\nimprove the computational performance of a source finding program. However, it\nis desirable to further reduce the processing time of source finding in order\nto decrease the computational resources required for the task. GPU acceleration\nis a method that may achieve significant increases in performance for some\nsource finding algorithms, particularly for filtering image data. This work\nconsiders the application of GPU acceleration to the task of source finding and\nthe techniques used to achieve the best performance, such as memory management.\nWe also examine the changes in performance, where the algorithms that were GPU\naccelerated achieved a speedup of around 3.2 times the 12 core per node\nCPU-only performance, while the program as a whole experienced a speedup of 2.0\ntimes.", "positive": "Hypercalibration: A Pan-STARRS1-based recalibration of the Sloan Digital\n Sky Survey: We present a recalibration of the Sloan Digital Sky Survey (SDSS) photometry\nwith new flat fields and zero points derived from Pan-STARRS1 (PS1). Using PSF\nphotometry of 60 million stars with $16 < r < 20$, we derive a model of\namplifier gain and flat-field corrections with per-run RMS residuals of 3\nmillimagnitudes (mmag) in $griz$ bands and 15 mmag in $u$ band. The new\nphotometric zero points are adjusted to leave the median in the Galactic North\nunchanged for compatibility with previous SDSS work. We also identify transient\nnon-photometric periods in SDSS (\"contrails\") based on photometric deviations\nco-temporal in SDSS bands. The recalibrated stellar PSF photometry of SDSS and\nPS1 has an RMS difference of {9,7,7,8} mmag in $griz$, respectively, when\naveraged over $15'$ regions." }, { "anchor": "Technosignatures in Transit: Kepler, K2, TESS, and similar time-domain photometric projects, while\ndesigned with exoplanet detection in mind, are also well-suited projects for\nsearches for large artificial structures orbiting other stars in the Galaxy. An\neffort to examine these data sets with an eye towards non-spherical or\notherwise anomalous transit events, and a robust follow-up program to\nunderstand the stars and occulters that generate them, would enable the first\nrobust upper limits on such megastructures in terms of their sizes, occurrence\nrates, and orbital properties. Such work also has the ancillary benefit of\nimproving our understanding of stellar photometric variability and orbital and\nphysical parameter estimation of exoplanets from photometric time series, and\nmay lead to the identification of new, unexpected classes of stellar variables\nand exoplanets. Ultimately, searching for the most unusual and anomalous\nsignatures benefits not only the search for technologies, but also the entire\nastronomical community by uncovering new mysteries to advance our understanding\nof the Universe.", "positive": "Digital Complex Correlator for a C-band Polarimetry survey: The international Galactic Emission Mapping project aims to map and\ncharacterize the polarization field of the Milky Way. In Portugal it will\ncartograph the C-band sky polarized emission of the Northern Hemisphere and\nprovide templates for map calibration and foreground control of microwave space\nprobes like ESA Planck Surveyor mission. The receiver system is equipped with a\nnovel receiver with a full digital back-end using an Altera Field Programmable\nGate Array, having a very favorable cost/performance relation. This new digital\nbackend comprises a base-band complex cross-correlator outputting the four\nStokes parameters of the incoming polarized radiation. In this document we\ndescribe the design and implementation of the complex correlator using COTS\ncomponents and a processing FPGA, detailing the method applied in the several\nalgorithm stages and suitable for large sky area surveys." }, { "anchor": "Assessments of Ali, Dome A, and Summit Camp for Mm-wave Observations\n Using MERRA-2 Reanalysis: The latest MERRA-2 reanalysis of the modern satellite measurements provides\nunprecedented uniformity and fidelity for the atmospheric data. In this paper,\nthese data are used to evaluate five sites for millimeter-wave (mm-wave)\nobservations. These include two established sites (South Pole and Chajnantor,\nAtacama), and three new sites (Ali, Tibet; Dome A, Antarctica; and Summit Camp,\nGreenland). Atmospheric properties including precipitable water vapor (PWV),\nsky brightness temperature fluctuations, ice and liquid water paths are derived\nand compared. Dome A emerges to be the best among those evaluated, with PWV and\nfluctuations smaller than the second-best site, South Pole, by more than a\nfactor of 2. It is found that the higher site in Ali (6,100 m) is on par with\nCerro Chajnantor (5,612 m) in terms of transmission and stability. The lower\nsite in Ali (5,250 m) planned for first stage of observations at 90/150GHz\nprovides conditions comparable to those on the Chajnantor Plateau. These\nanalyses confirm Ali to be an excellent mm-wave site on the Northern Hemisphere\nthat will complement well-established sites on the Southern Hemisphere. It is\nalso found in this analysis that the observing conditions at Summit Camp are\ncomparable to Cerro Chajnantor. Although it is more affected by the presence of\nliquid water clouds.", "positive": "SPECULOOS Northern Observatory: searching for red worlds in the northern\n skies: SPECULOOS is a ground-based transit survey consisting of six identical 1-m\nrobotic telescopes. The immediate goal of the project is to detect temperate\nterrestrial planets transiting nearby ultracool dwarfs (late M-dwarf stars and\nbrown dwarfs), which could be amenable for atmospheric research with the next\ngeneration of telescopes. Here, we report the developments of the northern\ncounterpart of the project - SPECULOOS Northern Observatory, and present its\nperformance during the first three years of operations from mid-2019 to\nmid-2022. Currently, the observatory consists of one telescope, which is named\nArtemis. The Artemis telescope demonstrates remarkable photometric precision,\nallowing it to be ready to detect new transiting terrestrial exoplanets around\nultracool dwarfs. Over the period of the first three years after the\ninstallation, we observed 96 objects from the SPECULOOS target list for 6000\nhours with a typical photometric precision of $0.5\\%$, and reaching a precision\nof $0.2\\%$ for relatively bright non-variable targets with a typical exposure\ntime of 25 sec. Our weather downtime (clouds, high wind speed, high humidity,\nprecipitation and/or high concentration of dust particles in the air) over the\nperiod of three years was 30% of overall night time. Our actual downtime is 40%\nbecause of additional time loss associated with technical problems." }, { "anchor": "Systematic Serendipity: A Test of Unsupervised Machine Learning as a\n Method for Anomaly Detection: Advances in astronomy are often driven by serendipitous discoveries. As\nsurvey astronomy continues to grow, the size and complexity of astronomical\ndatabases will increase, and the ability of astronomers to manually scour data\nand make such discoveries decreases. In this work, we introduce a machine\nlearning-based method to identify anomalies in large datasets to facilitate\nsuch discoveries, and apply this method to long cadence lightcurves from NASA's\nKepler Mission. Our method clusters data based on density, identifying\nanomalies as data that lie outside of dense regions. This work serves as a\nproof-of-concept case study and we test our method on four quarters of the\nKepler long cadence lightcurves. We use Kepler's most notorious anomaly,\nBoyajian's Star (KIC 8462852), as a rare `ground truth' for testing outlier\nidentification to verify that objects of genuine scientific interest are\nincluded among the identified anomalies. We evaluate the method's ability to\nidentify known anomalies by identifying unusual behavior in Boyajian's Star, we\nreport the full list of identified anomalies for these quarters, and present a\nsample subset of identified outliers that includes unusual phenomena, objects\nthat are rare in the Kepler field, and data artifacts. By identifying <4% of\neach quarter as outlying data, we demonstrate that this anomaly detection\nmethod can create a more targeted approach in searching for rare and novel\nphenomena.", "positive": "The ELT-MOS (MOSAIC): towards the construction phase: When combined with the huge collecting area of the ELT, MOSAIC will be the\nmost effective and flexible Multi-Object Spectrograph (MOS) facility in the\nworld, having both a high multiplex and a multi-Integral Field Unit (Multi-IFU)\ncapability. It will be the fastest way to spectroscopically follow-up the\nfaintest sources, probing the reionisation epoch, as well as evaluating the\nevolution of the dwarf mass function over most of the age of the Universe.\nMOSAIC will be world-leading in generating an inventory of both the dark matter\n(from realistic rotation curves with MOAO fed NIR IFUs) and the cool to\nwarm-hot gas phases in z=3.5 galactic haloes (with visible wavelenth IFUs).\nGalactic archaeology and the first massive black holes are additional targets\nfor which MOSAIC will also be revolutionary. MOAO and accurate sky subtraction\nwith fibres have now been demonstrated on sky, removing all low Technical\nReadiness Level (TRL) items from the instrument. A prompt implementation of\nMOSAIC is feasible, and indeed could increase the robustness and reduce risk on\nthe ELT, since it does not require diffraction limited adaptive optics\nperformance. Science programmes and survey strategies are currently being\ninvestigated by the Consortium, which is also hoping to welcome a few new\npartners in the next two years." }, { "anchor": "Optimal CCD readout by digital correlated double sampling: Digital correlated double sampling (DCDS), a readout technique for\ncharge-coupled devices (CCD), is gaining popularity in astronomical\napplications. By using an oversampling ADC and a digital filter, a DCDS system\ncan achieve a better performance than traditional analogue readout techniques\nat the expense of a more complex system analysis. Several attempts to analyse\nand optimize a DCDS system have been reported, but most of the work presented\nin the literature has been experimental. Some approximate analytical tools have\nbeen presented for independent parameters of the system, but the overall\nperformance and trade-offs have not been yet modelled. Furthermore, there is\ndisagreement among experimental results that cannot be explained by the\nanalytical tools available. In this work, a theoretical analysis of a generic\nDCDS readout system is presented, including key aspects such as the signal\nconditioning stage, the ADC resolution, the sampling frequency and the digital\nfilter implementation. By using a time-domain noise model, the effect of the\ndigital filter is properly modelled as a discrete-time process, thus avoiding\nthe imprecision of continuous-time approximations that have been used so far.\nAs a result, an accurate, closed-form expression for the signal-to-noise ratio\nat the output of the readout system is reached. This expression can be easily\noptimized in order to meet a set of specifications for a given CCD, thus\nproviding a systematic design methodology for an optimal readout system.\nSimulated results are presented to validate the theory, obtained with both\ntime- and frequency-domain noise generation models for completeness.", "positive": "The COSPIX mission: focusing on the energetic and obscured Universe: Tracing the formation and evolution of all supermassive black holes,\nincluding the obscured ones, understanding how black holes influence their\nsurroundings and how matter behaves under extreme conditions, are recognized as\nkey science objectives to be addressed by the next generation of instruments.\nThese are the main goals of the COSPIX proposal, made to ESA in December 2010\nin the context of its call for selection of the M3 mission. In addition,\nCOSPIX, will also provide key measurements on the non thermal Universe,\nparticularly in relation to the question of the acceleration of particles, as\nwell as on many other fundamental questions as for example the energetic\nparticle content of clusters of galaxies. COSPIX is proposed as an observatory\noperating from 0.3 to more than 100 keV. The payload features a single long\nfocal length focusing telescope offering an effective area close to ten times\nlarger than any scheduled focusing mission at 30 keV, an angular resolution\nbetter than 20 arcseconds in hard X-rays, and polarimetric capabilities within\nthe same focal plane instrumentation. In this paper, we describe the science\nobjectives of the mission, its baseline design, and its performances, as\nproposed to ESA." }, { "anchor": "The Gravitational-wave Optical Transient Observer (GOTO): The Gravitational-wave Optical Transient Observer (GOTO) is a wide-field\ntelescope project focused on detecting optical counterparts to\ngravitational-wave sources. Each GOTO robotic mount holds eight 40 cm\ntelescopes, giving an overall field of view of 40 square degrees. As of 2022\nthe first two GOTO mounts have been commissioned at the Roque de los Muchachos\nObservatory on La Palma, Canary Islands, and construction of the second node\nwith two additional 8-telescope mounts has begin at Siding Spring Observatory\nin New South Wales, Australia. Once fully operational each GOTO mount will be\nnetworked to form a robotic, multi-site observatory, which will survey the\nentire visible sky every two nights and enable rapid follow-up detections of\ntransient sources.", "positive": "Synthetic Modeling of Astronomical Closed Loop Adaptive Optics: We present an analytical model of a single natural guide star astronomical\nadaptive optics system, in closed loop mode. The model is used to simulate the\nlong exposure system point spread function, using the spatial frequency (or\nFourier) approach, and complement an initial open loop model. Applications\nrange from system design, science case analysis and AO data reduction. All the\nclassical phase errors have been included: deformable mirror fitting error,\nwavefront sensor spatial aliasing, wavefront sensor noise, and the correlated\nanisoplanatic and servo-lag error. The model includes the deformable mirror\nspatial transfer function, and the actuator array geometry can be different\nfrom the wavefront sensor lenslet array geometry. We also include the\ndispersion between the sensing and the correction wavelengths. Illustrative\nexamples are given at the end of the paper." }, { "anchor": "Sky Subtraction for LAMOST: Sky subtraction is the key technique in data reduction of multi-fiber\nspectra. Knowledge of the related instrument character is necessary to\ndetermine the method adopted in sky subtraction. In this study, we described\nthe sky subtraction method designed for LAMOST(Large sky Area Multi-Object\nfiber Spectroscopic Telescope) survey. The method has been intergrated into\nLAMOST 2D Pipeline v2.6 and applied to data of LAMOST DR3 and later. For\nLAMOST, sky emission line calibration is used to alleviate the\nposition-dependent (thus time-dependent) ~4% fiber throughput uncertainty and\nthe small wavelength instability (0.1\\AA ) during observation. PCA (Principal\nComponent Analysis) sky subtraction further reduces 25% of the sky line\nresidual of the OH lines in the red part of the LAMOST spectra after the mater\nsky spectrum, which is derived from a B-spline fit of 20 sky fibers in each\nspectrograph, is adjusted by sky emission line and subtracted from each fiber.\nFurther analysis shows that our wavelength calibration accuracy is about\n4.5km/s, and the average sky subtraction residuals are about 3% for sky\nemission lines and 3% for continuum region. The relative sky subtraction\nresiduals vary with the moon light background brightness, could reach as low as\n1.5% for the sky emission line regions in the dark night. Tests on the F stars\nof both similar sky emission line strength and similar object continuum\nintensity show that the sky emission line residual of LAMOST is smaller than\nthose of SDSS survey.", "positive": "Photometric precision of a Si:As impurity band conduction mid-infrared\n detector and application to transit spectroscopy: Transit spectroscopy is the most promising path toward characterizing nearby\nterrestrial planets at mid-infrared wavelengths in the next 20 years. The\nSpitzer Space telescope has achieved moderately good mid-infrared photometric\nprecision in observations of transiting planets, but the intrinsic photometric\nstability of mid-IR detectors themselves has not been reported in the\nscientific or technical literature. Here, we evaluated the photometric\nprecision of a JWST MIRI prototype mid-infrared Si:As impurity band conduction\ndetector, using time-series data taken under flood illumination. These\nmeasurements of photometric precision were conducted over periods of 10 hours,\nrepresentative of the time required to observe an exoplanet transit. After\nselecting multiple sub-regions with a size of 10x10 pixels and compensating for\na gain change caused by our warm detector control electronics for the selected\nsub-regions, we found that the photometric precision was limited to 26.3ppm at\nhigh co-added signal levels due to a gain variation caused by our warm detector\ncontrol electronics. The photometric precision was improved up to 12.8ppm after\ncorrecting for the gain drift. We also translated the photometric precision to\nthe expected spectro-photometric precision, assuming that an optimized\ndensified pupil spectrograph is used in transit observations. We found that the\nspectro-photometric precision of an optimized densified pupil spectrograph when\nused in transit observations is expected to be improved by the square root of\nthe number of pixels per a spectral resolution element. At the high co-added\nsignal levels, the total noise could be reduced down to 7ppm, which was larger\nby a factor of 1.3 than the ideal performance that was limited by the Poisson\nnoise and readout noise. The systematic noise hidden behind the simulated\ntransit spectroscopy was 1.7ppm." }, { "anchor": "Second generation Robo-AO instruments and systems: The prototype Robo-AO system at the Palomar Observatory 1.5-m telescope is\nthe world's first fully automated laser adaptive optics instrument. Scientific\noperations commenced in June 2012 and more than 12,000 observations have since\nbeen performed at the ~0.12\" visible-light diffraction limit. Two new infrared\ncameras providing high-speed tip-tilt sensing and a 2' field-of-view will be\nintegrated in 2014. In addition to a Robo-AO clone for the 2-m IGO and the\nnatural guide star variant KAPAO at the 1-m Table Mountain telescope, a second\ngeneration of facility-class Robo-AO systems are in development for the 2.2-m\nUniversity of Hawai'i and 3-m IRTF telescopes which will provide higher Strehl\nratios, sharper imaging, ~0.07\", and correction to {\\lambda} = 400 nm.", "positive": "Fiber scrambling for high-resolution spectrographs. II. A double fiber\n scrambler for Keck Observatory: We have designed a fiber scrambler as a prototype for the Keck HIRES\nspectrograph, using double scrambling to stabilize illumination of the\nspectrometer and a pupil slicer to increase spectral resolution to R = 70,000\nwith minimal slit losses. We find that the spectral line spread function (SLSF)\nfor the double scrambler observations is 18 times more stable than the SLSF for\ncomparable slit observations and 9 times more stable than the SLSF for a single\nfiber scrambler that we tested in 2010. For the double scrambler test data, we\nfurther reduced the radial velocity scatter from an average of 2.1 m/s to 1.5\nm/s after adopting a median description of the stabilized SLSF in our Doppler\nmodel. This demonstrates that inaccuracies in modeling the SLSF contribute to\nthe velocity RMS. Imperfect knowledge of the SLSF, rather than stellar jitter,\nsets the precision floor for chromospherically quiet stars analyzed with the\niodine technique using Keck HIRES and other slit-fed spectrometers. It is\nincreasingly common practice for astronomers to scale stellar noise in\nquadrature with formal errors such that their Keplerian model yields a\nchi-squared fit of 1.0. When this is done, errors from inaccurate modeling of\nthe SLSF (and perhaps from other sources) are attributed to the star and the\nfloor of the stellar noise is overestimated." }, { "anchor": "Asymptotic Orbits in Barred Spiral Galaxies: We study the formation of the spiral structure of barred spiral galaxies,\nusing an $N$-body model. The evolution of this $N$-body model in the adiabatic\napproximation maintains a strong spiral pattern for more than 10 bar rotations.\nWe find that this longevity of the spiral arms is mainly due to the phenomenon\nof stickiness of chaotic orbits close to the unstable asymptotic manifolds\noriginated from the main unstable periodic orbits, both inside and outside\ncorotation. The stickiness along the manifolds corresponding to different\nenergy levels supports parts of the spiral structure. The loci of the disc\nvelocity minima (where the particles spend most of their time, in the\nconfiguration space) reveal the density maxima and therefore the main\nmorphological structures of the system. We study the relation of these loci\nwith those of the apocentres and pericentres at different energy levels. The\ndiffusion of the sticky chaotic orbits outwards is slow and depends on the\ninitial conditions and the corresponding Jacobi constant.", "positive": "A versatile digital camera trigger for telescopes in the Cherenkov\n Telescope Array: This paper describes the concept of an FPGA-based digital camera trigger for\nimaging atmospheric Cherenkov telescopes, developed for the future Cherenkov\nTelescope Array (CTA). The proposed camera trigger is designed to select images\ninitiated by the Cherenkov emission of extended air showers from very-high\nenergy (VHE, E>20 GeV) photons and charged particles while suppressing\nsignatures from background light. The trigger comprises three stages. A first\nstage employs programmable discriminators to digitize the signals arriving from\nthe camera channels (pixels). At the second stage, a grid of low-cost FPGAs is\nused to process the digitized signals for camera regions with 37 pixels. At the\nthird stage, trigger conditions found independently in any of the overlapping\n37-pixel regions are combined into a global camera trigger by few central\nFPGAs. Trigger prototype boards based on Xilinx FPGAs have been designed, built\nand tested and were shown to function properly. Using these components a full\ncamera trigger with a power consumption and price per channel of about 0.5 W\nand 19 Euro, respectively, can be built. With the described design the camera\ntrigger algorithm can take advantage of pixel information in both the space and\nthe time domain allowing, for example, the creation of triggers sensitive to\nthe time-gradient of a shower image; the time information could also be\nexploited to online adjust the time window of the acquisition system for pixel\ndata. Combining the results of the parallel execution of different trigger\nalgorithms (optimized, for example, for the lowest and highest energies,\nrespectively) on each FPGA can result in a better response over all photons\nenergies (as demonstrated by Monte Carlo simulation in this work)." }, { "anchor": "Localizing FRBs through VLBI with the Algonquin Radio Observatory 10-m\n Telescope: The CHIME/FRB experiment has detected thousands of Fast Radio Bursts (FRBs)\ndue to its sensitivity and wide field of view; however, its low angular\nresolution prevents it from localizing events to their host galaxies. Very Long\nBaseline Interferometry (VLBI), triggered by FRB detections from CHIME/FRB will\nsolve the challenge of localization for non-repeating events. Using a\nrefurbished 10-m radio dish at the Algonquin Radio Observatory located in\nOntario Canada, we developed a testbed for a VLBI experiment with a theoretical\n~<30 masec precision. We provide an overview of the 10-m system and describe\nits refurbishment, the data acquisition, and a procedure for fringe fitting\nthat simultaneously estimates the geometric delay used for localization and the\ndispersive delay from the ionosphere. Using single pulses from the Crab pulsar,\nwe validate the system and localization procedure, and analyze the clock\nstability between sites, which is critical for phase-referencing an FRB event.\nWe find a localization of 50 masec is possible with the performance of the\ncurrent system. Furthermore, for sources with insufficient signal or restricted\nwideband to simultaneously measure both geometric and ionospheric delays, we\nshow that the differential ionospheric contribution between the two sites must\nbe measured to a precision of 1e-8 pc/cc to provide a reasonable localization\nfrom a detection in the 400--800 MHz band. Finally we show detection of an FRB\nobserved simultaneously in the CHIME and the Algonquin 10-m telescope, the\nfirst FRB cross-correlated in this very long baseline. This project serves as a\ntestbed for the forthcoming CHIME/FRB Outriggers project.", "positive": "Panoramic SETI: overall mechanical system design: PANOSETI (Pulsed All-Sky Near-infrared Optical Search for Extra Terrestrial\nIntelligence) is a dedicated SETI (Search for Extraterrestrial Intelligence)\nobservatory that is being designed to observe 4,441 sq. deg. to search for\nnano- to milli-second transient events. The experiment will have a dual\nobservatory system that has a total of 90 identical optical 0.48 m telescopes\nthat each have a 99 square degree field of view. The two observatory sites will\nbe separated by 1 km distance to help eliminate false positives and register a\ndefinitive signal. We discuss the overall mechanical design of the telescope\nmodules which includes a Fresnel lens housing, a shutter, three baffles, an\n32x32 array of Hamamatsu Multi-Photon Pixel Counting (MPPC) detectors that\nreside on a linear stage for focusing. Each telescope module will be housed in\na triangle of a 3rd tessellation frequency geodesic dome that has the ability\nto have directional adjustment to correct for manufacturing tolerances and\nastrometric alignment to the second observatory site. Each observatory will\nhave an enclosure to protect the experiment, and an observatory room for\noperations and electronics. We will review the overall design of the geodesic\ndomes and mechanical telescope attachments, as well as the overall cabling and\nobservatory infrastructure layout." }, { "anchor": "Exoplanet Transits as the Foundation of an Interstellar Communications\n Network: Two fundamental problems for extraterrestrial intelligences (ETIs) attempting\nto establish interstellar communication are timing and energy consumption.\nHumanity's study of exoplanets via their transit across the host star\nhighlights a means of solving both problems. An ETI 'A' can communicate with\nETI 'B' if B is observing transiting planets in A's star system, either by\nbuilding structures to produce artificial transits observable by B, or by\nemitting signals at B during transit, at significantly lower energy consumption\nthan typical electromagnetic transmission schemes.\n This can produce a network of interconnected civilisations, establishing\ncontact via observing each other's transits. Assuming that civilisations reside\nin a Galactic Habitable Zone (GHZ), I conduct Monte Carlo Realisation\nsimulations of the establishment and growth of this network, and analyse its\nproperties in the context of graph theory.\n I find that at any instant, only a few civilisations are correctly aligned to\ncommunicate via transits. However, we should expect the true network to be\ncumulative, where a \"handshake\" connection at any time guarantees connection in\nthe future via e.g. electromagnetic signals. In all our simulations, the\ncumulative network connects all civilisations together in a complete network.\nIf civilisations share knowledge of their network connections, the network can\nbe fully complete on timescales of order a hundred thousand years. Once\nestablished, this network can connect any two civilisations either directly, or\nvia intermediate civilisations, with a path much less than the dimensions of\nthe GHZ.", "positive": "Toward Eurasian SubMillimeter Telescopes: the concept of multicolor\n subTHz MKID-array demo camera MUSICAM and its instrumental testing: New challenges in submillimeter wave astronomy require instruments with a\ncombination of high sensitivity and angular resolution, wide field of view and\nmultiwave (multicolor) spectral range. New large single mm/submm telescopes are\nin high demand, as well as their inclusion in the global Event Horizon\nTelescope (EHT) VLBI network. At the same time, there are no large mm/submm\ntelescopes in Asia at all while appropriate sites exist and their appearance in\nAsia or Eurasia is long overdue. Kinetic inductance detectors (KID) are ideal\nfor large-format array implementation, which will be necessary for future\ntelescope development. Concept of multicolor subTHz KID-array MUSICAM demo\ncamera and its instrumental testing is given. It allows us to perform some\nnecessary steps toward the creation of the Eurasian SubMillimeter Telescopes\n(ESMT), which concept and scientific tasks are presented as well." }, { "anchor": "A Real-time Automatic Validation System for Optical Transients detected\n by GWAC: The ground-based wide-angle camera array (GWAC) generates millions of single\nframe alerts per night. After the complicated and elaborate filters by multiple\nmethods, a couple of dozens of candidates are still needed to be confirmed by\nfollow-up observations in real-time. In order to free scientists from the\ncomplex and high-intensity follow-up tasks, we developed a Real-time Automatic\ntransient Validation System (RAVS), and introduce here its system architecture,\ndata processing flow, database schema, automatic follow-up control flow, and\nmobile message notification solution. This system is capable of automatically\ncarrying out all operations in real-time without human intervention, including\nthe validation of transient candidates, the adaptive light-curve sampling for\nidentified targets in multi-band, and the pushing of observation results to the\nmobile client. The running of RAVS shows that an M-type stellar flare event can\nbe well sampled by RAVS without a significant loss of the details, while the\nobserving time is only less than one-third of the time coverage. Because the\ncontrol logic of RAVS is designed to be independent of the telescope hardware,\nRAVS can be conveniently transplanted to other telescopes, especially the\nfollow-up system of SVOM. Some future improvements are presented for the\nadaptive light-curve sampling, after taking into account both the brightness of\nsources and the evolution trends of the corresponding light-curves.", "positive": "Comparing NED and SIMBAD classifications across the contents of nearby\n galaxies: Cataloguing and classifying celestial objects is one of the fundamental\nactivities of observational astrophysics. In this work, we compare the contents\nof two comprehensive databases, the NASA Extragalactic Database (NED) and Set\nof Identifications, Measurements and Bibliography for Astronomical Data\n(SIMBAD) in the vicinity of nearby galaxies. These two databases employ\ndifferent classification schemes -- one flat and one hierarchical -- and our\ngoal was to determine the compatibility of classifications for objects in\ncommon. Searching both databases for objects within the respective isophotal\nradius of each of the ~1300 individual galaxies in the Local Volume Galaxy\nsample, we found that on average, NED contains about ten times as many entries\nas SIMBAD and about two thirds of SIMBAD objects are matched by position to a\nNED object, at 5 arcsecond tolerance. These quantities do not depend strongly\non the properties of the parent galaxies. We developed an algorithm to compare\nindividual object classifications between the two databases and found that 88%\nof the classifications agree; we conclude that NED and SIMBAD contain\nconsistent information for sources in common in the vicinity of nearby\ngalaxies. Because many galaxies have numerous sources contained only in one of\nNED or SIMBAD, researchers seeking the most complete picture of an individual\ngalaxy's contents are best served by using both databases." }, { "anchor": "Photometric Supernova Classification With Machine Learning: Automated photometric supernova classification has become an active area of\nresearch in recent years in light of current and upcoming imaging surveys such\nas the Dark Energy Survey (DES) and the Large Synoptic Survey Telescope, given\nthat spectroscopic confirmation of type for all supernovae discovered will be\nimpossible. Here, we develop a multi-faceted classification pipeline, combining\nexisting and new approaches. Our pipeline consists of two stages: extracting\ndescriptive features from the light curves and classification using a machine\nlearning algorithm. Our feature extraction methods vary from model-dependent\ntechniques, namely SALT2 fits, to more independent techniques fitting\nparametric models to curves, to a completely model-independent wavelet\napproach. We cover a range of representative machine learning algorithms,\nincluding naive Bayes, k-nearest neighbors, support vector machines, artificial\nneural networks and boosted decision trees (BDTs). We test the pipeline on\nsimulated multi-band DES light curves from the Supernova Photometric\nClassification Challenge. Using the commonly used area under the curve (AUC) of\nthe Receiver Operating Characteristic as a metric, we find that the SALT2 fits\nand the wavelet approach, with the BDTs algorithm, each achieves an AUC of\n0.98, where 1 represents perfect classification. We find that a representative\ntraining set is essential for good classification, whatever the feature set or\nalgorithm, with implications for spectroscopic follow-up. Importantly, we find\nthat by using either the SALT2 or the wavelet feature sets with a BDT\nalgorithm, accurate classification is possible purely from light curve data,\nwithout the need for any redshift information.", "positive": "The Nuclear Spectroscopic Telescope Array (NuSTAR): The Nuclear Spectroscopic Telescope Array (NuSTAR) is a NASA Small Explorer\nmission that will carry the first focusing hard X-ray (5 -- 80 keV) telescope\nto orbit. NuSTAR will offer a factor 50 -- 100 sensitivity improvement compared\nto previous collimated or coded mask imagers that have operated in this energy\nband. In addition, NuSTAR provides sub-arcminute imaging with good spectral\nresolution over a 12-arcminute field of view. After launch, NuSTAR will carry\nout a two-year primary science mission that focuses on four key programs:\nstudying the evolution of massive black holes through surveys carried out in\nfields with excellent multiwavelength coverage, understanding the population of\ncompact objects and the nature of the massive black hole in the center of the\nMilky Way, constraining explosion dynamics and nucleosynthesis in supernovae,\nand probing the nature of particle acceleration in relativistic jets in active\ngalactic nuclei. A number of additional observations will be included in the\nprimary mission, and a guest observer program will be proposed for an extended\nmission to expand the range of scientific targets. The payload consists of two\nco-aligned depth-graded multilayer coated grazing incidence optics focused onto\nsolid state CdZnTe pixel detectors. To be launched in early 2012 on a Pegasus\nrocket into a low-inclination Earth orbit. Data will be publicly available at\nGSFC's High Energy Astrophysics Science Archive Research Center (HEASARC)\nfollowing validation at the science operations center located at Caltech." }, { "anchor": "Demonstration of wideband metal mesh filters for submillimeter\n astrophysics using flexible printed circuits: We developed a wideband quasi-optical band-pass filter covering 170-520 GHz\nby exploiting the recent advancements in commercially available flexible\nprinted circuit (FPC) fabrication technologies. We designed and fabricated a\nthree-layered stack of loaded hexagonal grid metal meshes using a copper\npattern with a narrowest linewidth of $50~\\mu\\mathrm{m}$ on a polyimide\nsubstrate. The measured frequency pass-band shape was successfully reproduced\nthrough a numerical simulation using a set of parameters consistent with the\ndimensions of the fabricated metal meshes. FPC-based metal mesh filters will\nprovide a new pathway toward the on-demand development of\nmillimeter/submillimeter-wave quasi-optical filters at low cost and with a\nshort turnaround time.", "positive": "Frequency Domain Multiplexing for MKIDs: Comparing the Xilinx ZCU111\n RFSoC with their new 2x2 RFSoC board: The Xilinx ZCU111 Radio Frequency System on Chip (RFSoC) is a promising\nsolution for reading out large arrays of microwave kinetic inductance detectors\n(MKIDs). The board boasts eight on-chip 12-bit / 4.096 GSPS analogue-to-digital\nconverters (ADCs) and eight 14-bit / 6.554 GSPS digital-to-analogue converters\n(DACs), as well as field programmable gate array (FPGA) resources of 930,000\nlogic cells and 4,272 digital signal processing (DSP) slices. While this is\nsufficient data converter bandwidth for the readout of 8,000 MKIDs, with a 2\nMHz channel-spacing, and a 1 MHz sampling rate (per channel), additional FPGA\nresources are needed to perform the DSP needed to process this large number of\nMKIDs. A solution to this problem is the new Xilinx RFSoC 2x2 board. This board\ncosts only one fifth of the ZCU111 while still providing the same logic\nresources as the ZCU111, albeit with only a quarter of the data converter\nresources. Thus, using multiple RFSoC 2x2 boards would provide a better balance\nbetween FPGA resources and data converters, allowing the full utilization of\nthe RF bandwidth provided by the data converters, while also lowering the cost\nper pixel value of the readout system, from approximately EUR2.50 per pixel\nwith the ZCU111, to EUR1 per pixel." }, { "anchor": "VLBI for Gravity Probe B. III. A Limit on the Proper Motion of the\n \"Core\" of the Quasar 3C 454.3: We made VLBI observations at 8.4 GHz between 1997 and 2005 to estimate the\ncoordinates of the \"core\" component of the superluminal quasar, 3C 454.3, the\nultimate reference point in the distant universe for the NASA/Stanford\nGyroscope Relativity Mission, Gravity Probe B. These coordinates are determined\nrelative to those of the brightness peaks of two other compact extragalactic\nsources, B2250+194 and B2252+172, nearby on the sky, and within a celestial\nreference frame (CRF), defined by a large suite of compact extragalactic radio\nsources, and nearly identical to the International Celestial Reference Frame 2\n(ICRF2). We find that B2250+194 and B2252+172 are stationary relative to each\nother, and also in the CRF, to within 1-sigma upper limits of 15 and 30\nmicro-arcsec/yr in RA and decl., respectively. The core of 3C 454.3 appears to\njitter in its position along the jet direction over ~0.2 mas, likely due to\nactivity close to the putative supermassive black hole nearby, but on average\nis stationary in the CRF within 1-sigma upper limits on its proper motion of 39\nmicro-arcsec/yr (1.0c) and 30 micro-arcsec/yr (0.8c) in RA and decl.,\nrespectively, for the period 2002 - 2005. Our corresponding limit over the\nlonger interval, 1998 - 2005, of more importance to GP-B, is 46 and 56\nmicro-arcsec/yr in RA and decl., respectively. Some of 3C 454.3's jet\ncomponents show significantly superluminal motion with speeds of up to ~200\nmicro-arcsec/yr or 5c in the CRF. The core of 3C 454.3 thus provides for\nGravity Probe B a sufficiently stable reference in the distant universe.", "positive": "Antenna design for the SKA1-LOW and HERA super radio telescopes: This paper summarizes the design process and metrics for the latest antenna\ndesign for 2 radio telescopes, SKALA4 for the SKA1-LOW instrument and the\nV-feed for the HERA telescope. In the paper we briefly describe the main\nfeatures of the antenna element design and the most important figures of merit\nfor both instruments. Finally, we show the response of both designs against\nsome of these figures of merit." }, { "anchor": "Collision Avoidance in Next-generation Fiber Positioner Robotic System\n for Large Survey Spectrograph: Some of the next generation massive spectroscopic survey projects, such as\nDESI and PFS, plan to use thousands of fiber positioner robots packed at a\nfocal plane to quickly move in parallel the fiber-ends from the previous to the\nnext target points. The most direct trajectories are prone to collision that\ncould damage the robots and impact the survey operation. We thus present here a\nmotion planning method based on a novel decentralized navigation function for\ncollision-free coordination of fiber positioners. The navigation function takes\ninto account the configuration of positioners as well as the actuator\nconstraints. We provide details for the proof of convergence and collision\navoidance. Decentralization results in linear complexity for the motion\nplanning as well as dependency of motion duration with respect to the number of\npositioners. Therefore the coordination method is scalable for large-scale\nspectrograph robots. The short in-motion duration of positioner robots (~2.5\nseconds using typical actuator constraints), will thus allow the time dedicated\nfor observation to be maximized.", "positive": "Design and development of an ambient-temperature continuously-rotating\n achromatic half-wave plate for CMB polarization modulation on the POLARBEAR-2\n experiment: We describe the development of an ambient-temperature continuously-rotating\nhalf-wave plate (HWP) for study of the Cosmic Microwave Background (CMB)\npolarization by the POLARBEAR-2 (PB2) experiment. Rapid polarization modulation\nsuppresses 1/f noise due to unpolarized atmospheric turbulence and improves\nsensitivity to degree-angular-scale CMB fluctuations where the inflationary\ngravitational wave signal is thought to exist. A HWP modulator rotates the\ninput polarization signal and therefore allows a single polarimeter to measure\nboth linear polarization states, eliminating systematic errors associated with\ndifferencing of orthogonal detectors. PB2 projects a 365-mm-diameter focal\nplane of 7,588 dichroic, 95/150 GHz transition-edge-sensor bolometers onto a\n4-degree field of view that scans the sky at $\\sim$ 1 degree per second. We\nfind that a 500-mm-diameter ambient-temperature sapphire achromatic HWP\nrotating at 2 Hz is a suitable polarization modulator for PB2. We present the\ndesign considerations for the PB2 HWP, the construction of the HWP optical\nstack and rotation mechanism, and the performance of the fully-assembled HWP\ninstrument. We conclude with a discussion of HWP polarization modulation for\nfuture Simons Array receivers." }, { "anchor": "Mitigating Satellite Trails: a Study of Residual Light after Masking: Using Hyper Suprime Camera data (a precursor of what is to come with Rubin\nObservatory) we assess trail masking mitigation strategies for satellite\ncontamination. We examine HSC data of the Hubble COSMOS field where satellite\ntrails have been identified by eye. Exercising the current LSST Science\nPipelines on this data, we study the efficacy of masking satellite trails which\nappear in single visit exposures before they are assembled into a coadded\nframe. We find that the current routines largely mask satellite trails in\nsingle visits, but miss the extended low surface brightness features of the\nsatellite trails. For a sufficiently wide mask, these faint features appear at\na less significant level in the final coadd, as they are averaged down in a\nstack of tens of exposures. We study this print-through vs mask width. In this\nnote, we describe some of the challenges we encountered in that effort,\nprospects for more complete removal of the low surface brightness tails of the\nmasked trails, and possible science impacts.", "positive": "Proving the short-wavelength approximation in Pulsar Timing Array\n gravitational-wave background searches: A low-frequency gravitational-wave background (GWB) from the cosmic merger\nhistory of supermassive black holes is expected to be detected in the next few\nyears by pulsar timing arrays. A GWB induces distinctive correlations in the\npulsar residuals --- the expected arrival time of the pulse less its actual\narrival time. Simplifying assumptions are made in order to write an analytic\nexpression for this correlation function, called the Hellings and Downs curve\nfor an isotropic GWB, which depends on the angular separation of the pulsar\npairs, the gravitational-wave frequency considered, and the distance to the\npulsars. This is called the short-wavelength approximation, which we prove here\nrigorously and analytically for the first time." }, { "anchor": "On the efficiency of techniques for the reduction of impulsive noise in\n astronomical images: The impulsive noise in astronomical images originates from various sources.\nIt develops as a result of thermal generation in pixels, collision of cosmic\nrays with image sensor or may be induced by high readout voltage in Electron\nMultiplying CCD (EMCCD). It is usually efficiently removed by employing the\ndark frames or by averaging several exposures. Unfortunately, there are some\ncircumstances, when either the observed objects or positions of impulsive\npixels evolve and therefore each obtained image has to be filtered\nindependently. In this article we present an overview of impulsive noise\nfiltering methods and compare their efficiency for the purpose of astronomical\nimage enhancement. The employed set of noise templates consists of dark frames\nobtained from CCD and EMCCD cameras working on ground and in space. The\nexperiments conducted on synthetic and real images, allowed for drawing\nnumerous conclusions about the usefulness of several filtering methods for\nvarious: (1) widths of stellar profiles, (2) signal to noise ratios, (3) noise\ndistributions and (4) applied imaging techniques. The results of presented\nevaluation are especially valuable for selection of the most efficient\nfiltering schema in astronomical image processing pipelines.", "positive": "A framework for modeling the detailed optical response of thick,\n multiple segment, large format sensors for precision astronomy applications: Near-future astronomical survey experiments, such as LSST, possess system\nrequirements of unprecedented fidelity that span photometry, astrometry and\nshape transfer. Some of these requirements flow directly to the array of\nscience imaging sensors at the focal plane. Availability of high quality\ncharacterization data acquired in the course of our sensor development program\nhas given us an opportunity to develop and test a framework for simulation and\nmodeling that is based on a limited set of physical and geometric effects. In\nthis paper we describe those models, provide quantitative comparisons between\ndata and modeled response, and extrapolate the response model to predict\nimaging array response to astronomical exposure. The emergent picture departs\nfrom the notion of a fixed, rectilinear grid that maps photo-conversions to the\npotential well of the channel. In place of that, we have a situation where\nstructures from device fabrication, local silicon bulk resistivity variations\nand photo-converted carrier patterns still accumulating at the channel,\ntogether influence and distort positions within the photosensitive volume that\nmap to pixel boundaries. Strategies for efficient extraction of modeling\nparameters from routinely acquired characterization data are described. Methods\nfor high fidelity illumination/image distribution parameter retrieval, in the\npresence of such distortions, are also discussed." }, { "anchor": "Subtraction of test mass angular noise in the LISA Technology Package\n interferometer: We present recent sensitivity measurements of the LISA Technology Package\ninterferometer with articulated mirrors as test masses, actuated by\npiezo-electric transducers. The required longitudinal displacement resolution\nof 9 pm/sqrt[Hz] above 3 mHz has been demonstrated with an angular noise that\ncorresponds to the expected in on-orbit operation. The excess noise\ncontribution of this test mass jitter onto the sensitive displacement readout\nwas completely subtracted by fitting the angular interferometric data streams\nto the longitudinal displacement measurement. Thus, this cross-coupling\nconstitutes no limitation to the required performance of the LISA Technology\nPackage interferometry.", "positive": "Nonlinearity and wideband parametric amplification in an NbTiN\n microstrip transmission line: The nonlinear response associated with the current dependence of the\nsuperconducting kinetic inductance was studied in capacitively shunted NbTiN\nmicrostrip transmission lines. It was found that the inductance per unit length\nof one microstrip line could be changed by up to 20% by applying a DC current,\ncorresponding to a single pass time delay of 0.7 ns. To investigate nonlinear\ndissipation, Bragg reflectors were placed on either end of a section of this\ntype of transmission line, creating resonances over a range of frequencies.\nFrom the change in the resonance linewidth and amplitude with DC current, the\nratio of the reactive to the dissipative response of the line was found to be\n788. The low dissipation makes these transmission lines suitable for a number\nof applications that are microwave and millimeter-wave band analogues of\nnonlinear optical processes. As an example, by applying a millimeter-wave pump\ntone, very wide band parametric amplification was observed between about 3 and\n34 GHz. Use as a current variable delay line for an on-chip millimeter-wave\nFourier transform spectrometer is also considered." }, { "anchor": "Efficient Parallelization for AMR MHD Multiphysics Calculations;\n Implementation in AstroBEAR: Current AMR simulations require algorithms that are highly parallelized and\nmanage memory efficiently. As compute engines grow larger, AMR simulations will\nrequire algorithms that achieve new levels of efficient parallelization and\nmemory management. We have attempted to employ new techniques to achieve both\nof these goals. Patch or grid based AMR often employs ghost cells to decouple\nthe hyperbolic advances of each grid on a given refinement level. This\ndecoupling allows each grid to be advanced independently. In AstroBEAR we\nutilize this independence by threading the grid advances on each level with\npreference going to the finer level grids. This allows for global load\nbalancing instead of level by level load balancing and allows for greater\nparallelization across both physical space and AMR level. Threading of level\nadvances can also improve performance by interleaving communication with\ncomputation, especially in deep simulations with many levels of refinement. To\nimprove memory management we have employed a distributed tree algorithm that\nrequires processors to only store and communicate local sections of the AMR\ntree structure with neighboring processors.", "positive": "Optical Distortion in the NACO Imager: In this research note, we present a set of distortion solutions that may be\nused to correct geometric optical distortion in images taken with the S13\ncamera of the NACO adaptive optics imager." }, { "anchor": "Probing Accretion Turbulence in the Galactic Center with EHT Polarimetry: Magnetic fields grown by instabilities driven by differential rotation are\nbelieved to be essential to accretion onto black holes. These instabilities\nsaturate in a turbulent state; therefore, the spatial and temporal variability\nin the horizon-resolving images of Sagittarius A* (Sgr A*) will be able to\nempirically assess this critical aspect of accretion theory. However,\ninterstellar scattering blurs high-frequency radio images from the Galactic\ncenter and introduces spurious small-scale structures, complicating the\ninterpretation of spatial fluctuations in the image. We explore the impact of\ninterstellar scattering on the polarized images of Sgr A* and demonstrate that\nfor credible physical parameters, the intervening scattering is\nnon-birefringent. Therefore, we construct a scattering mitigation scheme that\nexploits horizon-resolving polarized millimeter/submillimeter VLBI observations\nto generate statistical measures of the intrinsic spatial fluctuations and\ntherefore the underlying accretion flow turbulence. An optimal polarization\nbasis is identified, corresponding to measurements of the fluctuations in\nmagnetic field orientation in three dimensions. We validate our mitigation\nscheme using simulated data sets and find that current and future ground-based\nexperiments will readily be able to accurately measure the image-fluctuation\npower spectrum.", "positive": "Receiver design for the REACH global 21-cm signal experiment: We detail the the REACH radiometric system designed to enable measurements of\nthe 21-cm neutral hydrogen line. Included is the radiometer architecture and\nend-to-end system simulations as well as a discussion of the challenges\nintrinsic to highly-calibratable system development. Following this, we share\nlaboratory results based on the calculation of noise wave parameters utilising\nan over-constrained least squares approach demonstrating a calibration RMSE of\n80 mK for five hours of integration on a custom-made source with comparable\nimpedance to that of the antenna used in the field. This paper therefore\ndocuments the state of the calibrator and data analysis in December 2022 in\nCambridge before shipping to South Africa." }, { "anchor": "Residual Entropy as a Diagnostic and Stopping Metric for CLEAN: We propose the use of entropy, measured from the spatial and flux\ndistribution of pixels in the residual image, as a potential diagnostic and\nstopping metric for the CLEAN algorithm. Despite its broad success as the\nstandard deconvolution approach in radio interferometry, finding the optimum\nstopping point for the iterative CLEAN algorithm is still a challenge. We show\nthat the entropy of the residual image, measured during the final stages of\nCLEAN, can be computed without prior knowledge of the source structure or\nexpected noise levels, and that finding the point of maximum entropy as a\nmeasure of randomness in the residual image serves as a robust stopping\ncriterion. We also find that, when compared to the expected thermal noise in\nthe image, the maximum entropy of the residuals is a useful diagnostic that can\nreveal the presence of data editing, calibration, or deconvolution issues that\nmay limit the fidelity of the final CLEAN map.", "positive": "HAWC Upgrade with a Sparse Outrigger Array: The High Altitude Water Cherenkov (HAWC) high-energy gamma-ray observatory\nhas recently been completed on the slopes of the Sierra Negra volcano in\ncentral Mexico. HAWC consists of 300 Water Cherenkov Detectors, each containing\n180 m$^3$ of ultra-purified water, that cover a total surface area of 20,000\nm$^2$. It detects and reconstructs cosmic- and gamma-ray showers in the energy\nrange of 100 GeV to 100 TeV. The HAWC trigger for the highest energy gammas\nreaches an effective area of 10$^5$ m$^2$ but many of them are poorly\nreconstructed because the shower core falls outside the array. An upgrade that\nincreases the present fraction of well reconstructed showers above 10 TeV by a\nfactor of 3-4 can be done with a sparse outrigger array of small water\nCherenkov detectors that pinpoint the core position and by that improve the\nangular resolution of the reconstructed showers. Such an outrigger array would\nbe of the order of 200 small water Cherenkov detectors of 2.5 m$^3$ placed over\nan area four times larger than HAWC. Detailed simulations are being performed\nto optimize the layout." }, { "anchor": "Bolidozor - Distributed radio meteor detection system: Most of the meteor radioastronomical radars are backscatter radars which\ncover only a small area of the atmosphere. Therefore a daytime meteor flux\nmodels are based on sparse data collected by only a few radar systems. To solve\nthis issue, a radar system with a wide coverage is required. We present a new\napproach of open-source multi-static radio meteor detection system which could\nbe distributed over a large area. This feature allows us to detect meteor\nevents taking place over a larger area as well and gather more uniform data\nabout meteor flux and possibly about meteor trajectories.", "positive": "IVOA Recommendation: HiPS - Hierarchical Progressive Survey: This document presents HiPS, a hierarchical scheme for the description,\nstorage and access of sky survey data. The system is based on hierarchical\ntiling of sky regions at finer and finer spatial resolution which facilitates a\nprogressive view of a survey, and supports multi-resolution zooming and\npanning. HiPS uses the HEALPix tessellation of the sky as the basis for the\nscheme and is implemented as a simple file structure with a direct indexing\nscheme that leads to practical implementations." }, { "anchor": "LensingETC: a tool to optimize multi-filter imaging campaigns of\n galaxy-scale strong lensing systems: Imaging data is the principal observable required to use galaxy-scale strong\nlensing in a multitude of applications in extragalactic astrophysics and\ncosmology. In this paper, we develop Lensing Exposure Time Calculator\n(LensingETC) to optimize the efficiency of telescope time usage when planning\nmulti-filter imaging campaigns for galaxy-scale strong lenses. This tool\nsimulates realistic data tailored to specified instrument characteristics and\nthen automatically models them to assess the power of the data in constraining\nlens model parameters. We demonstrate a use case of this tool by optimizing a\ntwo-filter observing strategy (in IR and UVIS) within the limited exposure time\nper system allowed by a Hubble Space Telescope (HST) Snapshot program. We find\nthat higher resolution is more advantageous to gain constraining power on the\nlensing observables, when there is a trade-off between signal-to-noise ratio\nand resolution; e.g., between the UVIS and IR filters of the HST. We also find\nthat, whereas a point spread function (PSF) with sub-Nyquist sampling allows\nthe sample mean for a model parameter to be robustly recovered for both\ngalaxy-galaxy and point-source lensing systems, a sub-Nyquist sampled PSF\nintroduces a larger scatter than a Nyquist sampled one in the deviation from\nthe ground truth for point-source lens systems.", "positive": "GIER: A Danish computer from 1961 with a role in the modern revolution\n of astronomy: A Danish computer, GIER, from 1961 played a vital role in the development of\na new method for astrometric measurement. This method, photon counting\nastrometry, ultimately led to two satellites with a significant role in the\nmodern revolution of astronomy. A GIER was installed at the Hamburg Observatory\nin 1964 where it was used to implement the entirely new method for the\nmeasurement of stellar positions by means of a meridian circle, then the\nfundamental instrument of astrometry. An expedition to Perth in Western\nAustralia with the instrument and the computer was a success. This method was\nalso implemented in space in the first ever astrometric satellite Hipparcos\nlaunched by ESA in 1989. The Hipparcos results published in 1997 revolutionized\nastrometry with an impact in all branches of astronomy from the solar system\nand stellar structure to cosmic distances and the dynamics of the Milky Way. In\nturn, the results paved the way for a successor, the one million times more\npowerful Gaia astrometry satellite launched by ESA in 2013. Preparations for a\nGaia successor in twenty years are making progress." }, { "anchor": "Enhanced models for stellar Doppler noise reveal hints of a 13-year\n activity cycle of 55 Cancri: We consider the impact of Doppler noise models on the statistical robustness\nof the exoplanetary radial-velocity fits. We show that the traditional model of\nthe Doppler noise with an additive jitter can generate large non-linearity\neffects, decreasing the reliability of the fit, especially in the cases when a\ncorreleated Doppler noise is involved. We introduce a regularization of the\nadditive noise model that can gracefully eliminate its singularities together\nwith the associated non-linearity effects.\n We apply this approach to Doppler time-series data of several exoplanetary\nsystems. It demonstrates that our new regularized noise model yields orbital\nfits that have either increased or at least the same statistical robustness, in\ncomparison with the simple additive jitter. Various statistical uncertainties\nin the parametric estimations are often reduced, while planet detection\nsignificance is often increased.\n Concerning the 55 Cnc five-planet system, we show that its Doppler data\ncontain significant correlated (\"red\") noise. Its correlation timescale is in\nthe range from days to months, and its magnitude is much larger than the effect\nof the planetary N-body perturbations in the radial velocity (these\nperturbations thus appear undetectable). Characteristics of the red noise\ndepend on the spectrograph/observatory, and also show a cyclic time variation\nin phase with the public Ca II H & K and photometry measurements. We interpret\nthis modulation as a hint of the long-term activity cycle of 55 Cnc, similar to\nthe Solar 11-year cycle. We estimate the 55 Cnc activity period by\n$12.6\\pm^{2.5}_{1.0}$ yrs, with the nearest minimum presumably expected in 2014\nor 2015.", "positive": "Computational Intelligence Challenges and Applications on Large-Scale\n Astronomical Time Series Databases: Time-domain astronomy (TDA) is facing a paradigm shift caused by the\nexponential growth of the sample size, data complexity and data generation\nrates of new astronomical sky surveys. For example, the Large Synoptic Survey\nTelescope (LSST), which will begin operations in northern Chile in 2022, will\ngenerate a nearly 150 Petabyte imaging dataset of the southern hemisphere sky.\nThe LSST will stream data at rates of 2 Terabytes per hour, effectively\ncapturing an unprecedented movie of the sky. The LSST is expected not only to\nimprove our understanding of time-varying astrophysical objects, but also to\nreveal a plethora of yet unknown faint and fast-varying phenomena. To cope with\na change of paradigm to data-driven astronomy, the fields of astroinformatics\nand astrostatistics have been created recently. The new data-oriented paradigms\nfor astronomy combine statistics, data mining, knowledge discovery, machine\nlearning and computational intelligence, in order to provide the automated and\nrobust methods needed for the rapid detection and classification of known\nastrophysical objects as well as the unsupervised characterization of novel\nphenomena. In this article we present an overview of machine learning and\ncomputational intelligence applications to TDA. Future big data challenges and\nnew lines of research in TDA, focusing on the LSST, are identified and\ndiscussed from the viewpoint of computational intelligence/machine learning.\nInterdisciplinary collaboration will be required to cope with the challenges\nposed by the deluge of astronomical data coming from the LSST." }, { "anchor": "yonder: A python package for data denoising and reconstruction: We present a standalone implementation of a data-deconvolution method based\non singular value decomposition. The tool is written in python and packaged in\nthe open-source yonder package. yonder receives as input two matrices, one for\nthe data and another for the errors, and outputs a denoised version of the\noriginal dataset. In this Research Note, we briefly describe the methodology\nand show a demonstration of the yonder on a simulated dataset.", "positive": "Query Driven Visualization of Astronomical Catalogs: Interactive visualization of astronomical catalogs requires novel techniques\ndue to the huge volumes and complex structure of the data produced by existing\nand upcoming astronomical surveys. The creation as well as the disclosure of\nthe catalogs can be handled by data pulling mechanisms. These prevent\nunnecessary processing and facilitate data sharing by having users request the\ndesired end products.\n In this work we present query driven visualization as a logical continuation\nof data pulling. Scientists can request catalogs in a declarative way and set\nprocess parameters directly from within the visualization. This results in\nprofound interoperation between software with a high level of abstraction.\n New messages for the Simple Application Messaging Protocol are proposed to\nachieve this abstraction. Support for these messages are implemented in the\nAstro-WISE information system and in a set of demonstrational applications." }, { "anchor": "NIFTy 3 - Numerical Information Field Theory - A Python framework for\n multicomponent signal inference on HPC clusters: NIFTy, \"Numerical Information Field Theory\", is a software framework designed\nto ease the development and implementation of field inference algorithms. Field\nequations are formulated independently of the underlying spatial geometry\nallowing the user to focus on the algorithmic design. Under the hood, NIFTy\nensures that the discretization of the implemented equations is consistent.\nThis enables the user to prototype an algorithm rapidly in 1D and then apply it\nto high-dimensional real-world problems. This paper introduces NIFTy 3, a major\nupgrade to the original NIFTy framework. NIFTy 3 allows the user to run\ninference algorithms on massively parallel high performance computing clusters\nwithout changing the implementation of the field equations. It supports\nn-dimensional Cartesian spaces, spherical spaces, power spaces, and product\nspaces as well as transforms to their harmonic counterparts. Furthermore, NIFTy\n3 is able to treat non-scalar fields. The functionality and performance of the\nsoftware package is demonstrated with example code, which implements a real\ninference algorithm from the realm of information field theory. NIFTy 3 is\nopen-source software available under the GNU General Public License v3 (GPL-3)\nat https://gitlab.mpcdf.mpg.de/ift/NIFTy/", "positive": "Characterizing Atacama B-mode Search Detectors with a Half-Wave Plate: The Atacama B-Mode Search (ABS) instrument is a cryogenic ($\\sim$10 K)\ncrossed-Dragone telescope located at an elevation of 5190 m in the Atacama\nDesert in Chile that observed for three seasons between February 2012 and\nOctober 2014. ABS observed the Cosmic Microwave Background (CMB) at large\nangular scales ($40<\\ell<500$) to limit the B-mode polarization spectrum around\nthe primordial B-mode peak from inflationary gravity waves at $\\ell \\sim100$.\nThe ABS focal plane consists of 480 transition-edge sensor (TES) bolometers.\nThey are coupled to orthogonal polarizations from a planar ortho-mode\ntransducer (OMT) and observe at 145 GHz. ABS employs an ambient-temperature,\nrapidly rotating half-wave plate (HWP) to mitigate systematic effects and move\nthe signal band away from atmospheric $1/f$ noise, allowing for the recovery of\nlarge angular scales. We discuss how the signal at the second harmonic of the\nHWP rotation frequency can be used for data selection and for monitoring the\ndetector responsivities." }, { "anchor": "Towards an automatic processing of CCD images with CPCS 2.0: We present a new automatic tool for time-domain astronomy - the Cambridge\nPhotometric Calibration Server 2.0 - developed under OPTICON H2020 programme.\nIt has been designed to respond to the need of automated rapid photometric data\ncalibration and dissemination for transient events, primarily from Gaia space\nmission. CPCS has been in operation since 2013 and has been used to calibrate\naround 130 000 observations of hundreds of transients. We present the status of\nthis tool's development and demonstrate improvements made in the second\nversion. The tests present the ability to combine CCD imaging data from\nmultiple telescopes and a whole variety of instruments. New tool provides\nscience-ready photometric data within minutes from observations in the\nautomatic manner.", "positive": "PIONIER: a visitor instrument for the VLTI: PIONIER is a 4-telescope visitor instrument for the VLTI, planned to see its\nfirst fringes in 2010. It combines four ATs or four UTs using a pairwise ABCD\nintegrated optics combiner that can also be used in scanning mode. It provides\nlow spectral resolution in H and K band. PIONIER is designed for imaging with a\nspecific emphasis on fast fringe recording to allow closure-phases and\nvisibilities to be precisely measured. In this work we provide the detailed\ndescription of the instrument and present its updated status." }, { "anchor": "The International X-ray Observatory - RFI#2: The International X-ray Observatory (IXO) is a joint NASA-ESA-JAXA effort.\nX-ray observations will resolve pressing astrophysical questions such as: What\nhappens close to a black hole? How do supermassive black holes grow? How does\nlarge scale structure form? What is the connection between these processes? To\naddress these questions requires dramatic increases in collection area combined\nwith sensitive new instrumentation. IXO's spectroscopic, timing, and\npolarimetric capabilities will probe close to the event horizon of\nsuper-massive black holes (SMBH) where strong gravity dominates. IXO will\ndetermine the evolution and origin of SMBH by measuring their spin to\nunderstand their merger history, surveying them to find their luminosity\ndistribution out to high redshift (z~8), and spectroscopically characterizing\ntheir outflows during peak activity. IXO will revolutionize our understanding\nof galaxy clusters by mapping their bulk motions and turbulence. IXO will\nobserve the process of cosmic feedback where black holes inject energy on\ngalactic and intergalactic scales, and characterize the missing baryons in the\ncosmic web. Meanwhile, surveys of distant clusters will constrain cosmological\nmodels. IXO will be available to all astronomers, taking X-ray astrophysics\nfrom an era where high-resolution spectra are a rarity to one with vast numbers\nof spectra from all types of sources. Powerful spectral diagnostics and large\ncollecting areas will reveal unexpected discoveries, with IXO studying new\nphenomena as they appear-a key feature of great observatories.", "positive": "An Evolving Solar Data Environment: The rapid growth of solar data is driving changes in the typical workflow and\nalgorithmic approach to solar data analysis. We present recently deployed tools\nto aid this evolution and layout the path for future development. The majority\nof space-based datasets including those from the multi-petabyte Solar Dynamics\nObservatory and the Hinode and Interface Region Imaging Spectrograph (IRIS)\nmissions are made available to the community through a common API with support\nin IDL (via SolarSoft), Python/SunPy and other emerging languages. Stellar\nastronomers may find the IRIS data particularly useful for research into\nstellar chromospheres and for interpreting UV spectra." }, { "anchor": "Novel directed search strategy to detect continuous gravitational waves\n from neutron stars in low- and high-eccentricity binary systems: We describe a novel, very fast and robust, directed search incoherent method\nfor periodic gravitational waves (GWs) from neutron stars in binary systems. As\ndirected search, we assume the source sky position to be known with enough\naccuracy, but all other parameters are supposed to be unknown. We exploit the\nfrequency-modulation due to source orbital motion to unveil the signal\nsignature by commencing from a collection of time and frequency peaks. We\nvalidate our pipeline adding 131 artificial continuous GW signals from pulsars\nin binary systems to simulated detector Gaussian noise, characterized by a\npower spectral density Sh = 4x10^-24 Hz^-1/2 in the frequency interval [70,\n200] Hz, which is overall commensurate with the advanced detector design\nsensitivities. The pipeline detected 128 signals, and the weakest signal\ninjected and detected has a GW strain amplitude of ~10^-24, assuming one month\nof gapless data collected by a single advanced detector. We also provide\nsensitivity estimations, which show that, for a single- detector data covering\none month of observation time, depending on the source orbital Doppler\nmodulation, we can detect signals with an amplitude of ~7x10^-25. By using\nthree detectors, and one year of data, we would easily gain more than a factor\n3 in sensitivity, translating into being able to detect weaker signals. We also\ndiscuss the parameter estimate proficiency of our method, as well as\ncomputational budget, which is extremely cheap. In fact, sifting one month of\nsingle-detector data and 131 Hz-wide frequency range takes roughly 2.4 CPU\nhours. Due to the high computational speed, the current procedure can be\nreadily applied in ally-sky schemes, sieving in parallel as many sky positions\nas permitted by the available computational power.", "positive": "AO3000 at Subaru: Combining for the first time a NIR WFS using First\n Light's C-RED ONE and ALPAO's 64x64 DM: After 16 years of on-sky operation, Subaru Telescope's facility adaptive\noptics AO188 is getting several major upgrades to become the extreme-AO AO3000\n(3000 actuators in the pupil compared to 188 previously). AO3000 will provide\nhigh-Strehl images for several instruments from visible to mid-infrared,\nnotably the Infrared Camera and Spectrograph (IRCS), and the Subaru\nCoronagraphic Extreme Adaptive Optics (SCExAO). For this upgrade, the original\n188-element deformable mirror (DM) will be replaced with ALPAO's $64\\times64$\nDM. The visible wavefront sensor will also be upgraded at a later date, but in\nthe meantime we are adding a near-infrared Wavefront Sensor (NIR WFS), using\neither a double roof prism pyramid mode or a focal plane WFS mode. This new\nwavefront sensor will use for the first time First Light's C-RED ONE camera,\nallowing for a full control of the $64\\times64$ DM at up to 1.6 kHz. One of the\nchallenges is the use of non-destructive reads and a rolling shutter with the\nmodulated pyramid. This upgrade will be particularly exciting for SCExAO, since\nthe extreme-AO loop will focus more on creating high-contrast dark zones\ninstead of correcting large atmospheric residuals. It will be the first time\ntwo extreme-AO loops will be combined on the same telescope. Finally, the setup\nAO3000+SCExAO+IRCS will serve as a perfect demonstrator for the Thirty Meter\nTelescope's Planetary Systems Imager (TMT-PSI). We will present here the\ndesign, integration and testing of AO3000, and show the first on-sky results." }, { "anchor": "OmniUV: A Multi-Purpose Simulation Toolkit for VLBI Observation: We present OmniUV, a multi-purpose simulation toolkit for space and ground\nVLBI observations. It supports various kinds of VLBI stations, including Earth\n(ground) fixed, Earth orbit, Lunar fixed, Lunar orbit, Moon-Earth and Earth-Sun\nLagrange 1 and 2 points, etc. The main functionalities of this toolkit are: (1)\nTrajectory calculation; (2) Baseline uv calculation, by taking the vailability\nof each station into account; (3) Visibility simulation for the given uv\ndistribution, source structure and system noise; (4) Image and beam\nreconstruction. Two scenarios, namely space VLBI network and wide field array,\nare presented as demonstrations of the toolkit applications in completely\ndifferent scales. OmniUV is the acronym of \"Omnipotent UV\". We hope it could\nwork as a general framework, in which various kinds of stations could be easily\nincorporated and the functionalities could be further extended. The toolkit has\nbeen made publicly available.", "positive": "Astro-WISE Information System: Astro-WISE is a scientific information system for the data processing of\noptical images. In this paper we review main features of Astro-WISE and\ndescribe the current status of the system." }, { "anchor": "Method for all-sky searches of continuous gravitational wave signals\n using the frequency-Hough transform: In this paper we present a hierarchical data analysis pipeline for all-sky\nsearches of continuous gravitational wave signals, like those emitted by\nspinning neutron stars asymmetric with respect to the rotation axis, with\nunknown position, rotational frequency and spin-down. The core of the pipeline\nis an incoherent step based on a particularly efficient implementation of the\nHough transform, that we call frequency-Hough, that maps the data\ntime-frequency plane to the source frequency/spin-down plane for each fixed\ndirection in the sky. Theoretical ROCs and sensitivity curves are computed and\nthe dependency on various thresholds is discussed. A comparison of the\nsensitivity loss with respect to an \"optimal\" method is also presented. Several\nother novelties, with respect to other wide-parameter analysis pipelines, are\nalso outlined. They concern, in particular, the construction of the grid in the\nparameter space, with over-resolution in frequency and parameter refinement,\ncandidate selection and various data cleaning steps which are introduced to\nimprove search sensitivity and rejection of false candidates.", "positive": "Morphological Classification of Radio Galaxies using Semi-Supervised\n Group Equivariant CNNs: Out of the estimated few trillion galaxies, only around a million have been\ndetected through radio frequencies, and only a tiny fraction, approximately a\nthousand, have been manually classified. We have addressed this disparity\nbetween labeled and unlabeled images of radio galaxies by employing a\nsemi-supervised learning approach to classify them into the known\nFanaroff-Riley Type I (FRI) and Type II (FRII) categories. A Group Equivariant\nConvolutional Neural Network (G-CNN) was used as an encoder of the\nstate-of-the-art self-supervised methods SimCLR (A Simple Framework for\nContrastive Learning of Visual Representations) and BYOL (Bootstrap Your Own\nLatent). The G-CNN preserves the equivariance for the Euclidean Group E(2),\nenabling it to effectively learn the representation of globally oriented\nfeature maps. After representation learning, we trained a fully-connected\nclassifier and fine-tuned the trained encoder with labeled data. Our findings\ndemonstrate that our semi-supervised approach outperforms existing\nstate-of-the-art methods across several metrics, including cluster quality,\nconvergence rate, accuracy, precision, recall, and the F1-score. Moreover,\nstatistical significance testing via a t-test revealed that our method\nsurpasses the performance of a fully supervised G-CNN. This study emphasizes\nthe importance of semi-supervised learning in radio galaxy classification,\nwhere labeled data are still scarce, but the prospects for discovery are\nimmense." }, { "anchor": "Low-Mass WIMP Sensitivity and Statistical Discrimination of Electron and\n Nuclear Recoils by Varying Luke-Neganov Phonon Gain in Semiconductor\n Detectors: Amplifying the phonon signal in a semiconductor dark matter detector can be\naccomplished by operating at high voltage bias and converting the electrostatic\npotential energy into Luke-Neganov phonons. This amplification method has been\nvalidated at up to |E|=40V/cm without producing leakage in CDMSII Ge detectors,\nallowing sensitivity to a benchmark WIMP with mass = 8GeV and cross section\n1.8e-42cm^2 assuming flat electronic recoil backgrounds near threshold.\nFurthermore, for the first time we show that differences in Luke-Neganov gain\nfor nuclear and electronic recoils can be used to discriminate statistically\nbetween low-energy background and a hypothetical WIMP signal by operating at\ntwo distinct voltage biases. Specifically, 99% of events have p-value<1e-8 for\na simulated 20kg-day experiment with a benchmark WIMP signal with mass =8GeV\nand cross section =3.3e-41cm^2.", "positive": "Feasibility of Cosmic Microwave Background Observations using\n Radiometers based on Whispering Gallery Mode Resonators: The fundamentals of the whispering gallery mode (WGM) resonators are well\nestablished in the literature, with several successful proof-of-concept\nexperiments. One remarkable benefit of this technology is the room-temperature\noperation. This characteristic could be used to build a new generation of\nradiometers that do not need to be cooled down to cryogenic temperatures to\nreach high sensitivities. In this article, a study of the viability of\ntechnological transfer is undertaken, beginning with a brief review of the\ntheoretical background that will be applied and leading to a proposal for a\nnovel spectro-polarimeter design. Simulations for a radiometer based on WGM\nresonance are analyzed and compared with state-of-the-art coherent receivers.\nThe results are then discussed, finding that although promising, WGM technology\nneeds R\\&D in several directions in order to be competitive, whose are\nsuggested by the authors with the idea of inspiring the work of the researchers\nin the field towards a new direction or approach." }, { "anchor": "Representation of light pressure resultant force and moment as a tensor\n series: In this article we address a problem of determination of light pressure upon\nspace structures of the complex geometric shape. For the surface element, we\nwrote a condition that this element can interact with light only from the front\nside, not from the back side. This condition To in the form of series of\nChebyshev polynomials of the first kind. Chebyshev expansion lets us move to\nthe series of tensors of increasing rank for the problem of determination of\nforce and moment. We obtained expressions for the fiber method for\ndetermination of light pressure on space structures of complex geometry taking\ninto account self--shadowing and reflections within the structure. We also give\nthe expressions for tensor parametrization by the specularity coefficient in\ncase of specular-diffuse reflection. For these expressions we calculated the\nprincipal moment and force upon two-sided flat solar sail, spherical and\ncylindrical bodies, and approximated light pressure upon a perspective space\nobservatory Millimetron. The proposed expressions can be used in the ballistic\nanalysis of solar sails and other space objects, which are significantly\naffected by the radiation pressure. Also, these results can be used to analyze\nthe dynamics of movement of large-scale space structures around the center of\ngravity under the light pressure.", "positive": "High-resolution imaging and spectroscopy in the visible from large\n ground-based telescopes with natural guide stars: Near-diffraction limited imaging and spectroscopy in the visible on large\n(8-10 meter) class telescopes has proved to be beyond the capabilities of\ncurrent adaptive optics technologies, even when using laser guide stars. The\nneed for high resolution visible imaging in any part of the sky suggests that a\nrather different approach is needed. This paper describes the results of\nsimulations, experiments and astronomical observations that show that a\ncombination of low order adaptive optic correction using a 4-field curvature\nsensor and fast Lucky Imaging strategies with a photon counting CCD camera\nsystems should deliver 20-25 milliarcsecond resolution in the visible with\nreference stars as faint as 18.5 magnitude in I band on large telescopes. Such\nan instrument may be used to feed an integral field spectrograph efficiently\nusing configurations that will also be described." }, { "anchor": "High-contrast imaging of tight resolved binaries with two vector vortex\n coronagraphs in cascade with the Palomar SDC instrument: More than half of the stars in the solar neighborhood reside in\nbinary/multiple stellar systems, and recent studies suggest that gas giant\nplanets may be more abundant around binaries than single stars. Yet, these\nmultiple systems are usually overlooked or discarded in most direct imaging\nsurveys, as they prove difficult to image at high-contrast using coronographs.\nThis is particularly the case for compact binaries (less than 1\" angular\nseparation) with similar stellar magnitudes, where no existing coronagraph can\nprovide high-contrast regime. Here we present preliminary results of an\non-going Palomar pilot survey searching for low-mass companions around ~15\nyoung challenging binary systems, with angular separation as close as 0\".3 and\nnear-equal K-band magnitudes. We use the Stellar Double Coronagraph (SDC)\ninstrument on the 200-inch Telescope in a modified optical configuration,\nmaking it possible to align any targeted binary system behind two vector vortex\ncoronagraphs in cascade. This approach is uniquely possible at Palomar, thanks\nto the absence of sky rotation combined with the availability of an extreme AO\nsystem, and the number of intermediate focal-planes provided by the SDC\ninstrument. Finally, we expose our current data reduction strategy, and we\nattempt to quantify the exact contrast gain parameter space of our approach,\nbased on our latest observing runs.", "positive": "Data-driven photometric redshift estimation from type Ia supernovae\n light curves: Redshift measurement has always been a constant need in modern astronomy and\ncosmology. And as new surveys have been providing an immense amount of data on\nastronomical objects, the need to process such data automatically proves to be\nincreasingly necessary. In this article, we use simulated data from the Dark\nEnergy Survey, and from a pipeline originally created to classify supernovae,\nwe developed a linear regression algorithm optimized through novel automated\nmachine learning (AutoML) frameworks achieving an error score better than\nordinary data pre-processing methods when compared with other modern algorithms\n(such as XGBOOST). Numerically, the photometric prediction RMSE of type Ia\nsupernovae events was reduced from 0.16 to 0.09 and the RMSE of all supernovae\ntypes decreased from 0.20 to 0.14. Our pipeline consists of four steps: through\nspectroscopic data points we interpolate the light curve using Gaussian process\nfitting algorithm, then using a wavelet transform we extract the most important\nfeatures of such curves; in sequence we reduce the dimensionality of such\nfeatures through principal component analysis, and in the end we applied super\nlearning techniques (stacked ensemble methods) through an AutoML framework\ndedicated to optimize the parameters of several different machine learning\nmodels, better resolving the problem. As a final check, we obtained probability\ndistribution functions (PDFs) using Gaussian kernel density estimations through\nthe predictions of more than 50 models trained and optimized by AutoML. Those\nPDFs were calculated to replicate the original curves that used SALT2 model, a\nmodel used for the simulation of the raw data itself." }, { "anchor": "Measurements of Antenna Surface for Millimeter-Wave Space Radio\n Telescope: In the construction of a space radio telescope, it is essential to use\nmaterials with a low noise factor and high mechanical robustness for the\nantenna surface. We present the results of measurements of the reflection\nperformance of two candidates for antenna surface materials for use in a radio\ntelescope installed in a new millimeter-wave astronomical satellite, ASTRO-G.\nTo estimate the amount of degradation caused by fluctuations in the thermal\nenvironment in the projected orbit of the satellite, a thermal cycle test was\ncarried out for two candidates, namely, copper foil carbon fiber reinforced\nplastic (CFRP) and aluminum-coated CFRP. At certain points during the thermal\ncycle test, the reflection loss of the surfaces was measured precisely by using\na radiometer in the 41-45 GHz band. In both candidates, cracks appeared on the\nsurface after the thermal cycle test, where the number density of the cracks\nincreased as the thermal cycle progressed. The reflection loss also increased\nin proportion to the number density of the cracks. Nevertheless, the loss of\nthe copper foil surface met the requirements of ASTRO-G at the end of the\nequivalent life, whereas that of the aluminum-coated surface exceeded the\nmaximal value in the requirement even before the end of the cycle.", "positive": "Towards the First Catalog of Fermi-LAT sources below 100 MeV: Previous analyses of point sources in the gamma-ray range were done either\nbelow 30 MeV or above 100 MeV. Below 30 MeV, the imaging Compton telescope\n(COMPTEL) onboard NASA's Compton Gamma-Ray Observatory detected 26 steady\nsources in the energy range from 0.75 to 30 MeV. At high energy, the Fermi\nLarge Area Telescope (LAT) has detected more than three thousand sources\nbetween 100 MeV and 300 GeV. Since the Fermi LAT detects gamma rays also below\n100 MeV, we apply a point source detection algorithm in the energy range\nbetween 30 MeV and 100 MeV. In the analysis we use PGWave, which is a\nbackground independent tool based on a wavelet transform." }, { "anchor": "The Case for Non-Cryogenic Comet Nucleus Sample Return: Comets hold answers to mysteries of the Solar System by recording presolar\nhistory, the initial states of planet formation and prebiotic organics and\nvolatiles to the early Earth. Analysis of returned samples from a comet nucleus\nwill provide unparalleled knowledge about the Solar System starting materials\nand how they came together to form planets and give rise to life:\n 1. How did comets form?\n 2. Is comet material primordial, or has it undergone a complex alteration\nhistory?\n 3. Does aqueous alteration occur in comets?\n 4. What is the composition of cometary organics?\n 5. Did comets supply a substantial fraction of Earth's volatiles?\n 6. Did cometary organics contribute to the homochirality in life on Earth?\n 7. How do complex organic molecules form and evolve in interstellar, nebular,\nand planetary environments?\n 8. What can comets tell us about the mixing of materials in the protosolar\nnebula?", "positive": "PIONIER: a 4-telescope visitor instrument at VLTI: PIONIER stands for Precision Integrated-Optics Near-infrared Imaging\nExpeRiment. It combines four 1.8m Auxilliary Telescopes or four 8m Unit\nTelescopes of the Very Large Telescope Interferometer (ESO, Chile) using an\nintegrated optics combiner. The instrument has been integrated at IPAG starting\nin December 2009 and commissioned at the Paranal Observatory in October 2010.\nIt provides scientific observations since November 2010. In this paper, we\ndetail the instrumental concept, we describe the standard operational modes and\nthe data reduction strategy. We present the typical performance and discuss how\nto improve them. This paper is based on laboratory data obtained during the\nintegrations at IPAG, as well as on-sky data gathered during the commissioning\nat VLTI. We illustrate the imaging capability of PIONIER on the binaries\ndeltaSco and HIP11231. PIONIER provides 6 visibilities and 3 independent\nclosure phases in the H band, either in a broadband mode or with a low spectral\ndispersion (R=40), using natural light (i.e. unpolarized). The limiting\nmagnitude is Hmag=7 in dispersed mode under median atmospheric conditions\n(seeing<1\", tau0>3ms) with the 1.8m Auxiliary Telescopes. We demonstrate a\nprecision of 0.5deg on the closure phases. The precision on the calibrated\nvisibilities ranges from 3 to 15% depending on the atmospheric conditions.\nPIONIER has been installed and successfully tested as a visitor instrument for\nthe VLTI. It permits high angular resolution imaging studies at an\nunprecedented level of sensitivity. The successful combination of the four 8m\nUnit Telescopes in March 2011 demonstrates that VLTI is ready for 4-telescope\noperation." }, { "anchor": "Characterization of Solar Telescope Polarization Properties Across the\n Visible and Near-Infrared Spectrum. Case Study: The Dunn Solar Telescope: Accurate astrophysical polarimetry requires a proper characterization of the\npolarization properties of the telescope and instrumentation employed to obtain\nthe observations. Determining the telescope and instrument Muller matrix is\nbecoming increasingly difficult with the increase in aperture size of the new\nand upcoming solar telescopes. We have carried out a detailed multi-wavelength\ncharacterization of the Dunn Solar Telescope (DST) at the National Solar\nObservatory/Sacramento Peak as a case study and explore various possibilites\nfor the determination of its polarimetric properties. We show that the\ntelescope model proposed in this paper is more suitable than that in previous\nwork in that it describes better the wavelength dependence of aluminum-coated\nmirrors. We explore the adequacy of the degrees of freedom allowed by the model\nusing a novel mathematical formalism. Finally, we investigate the use of\npolarimeter calibration data taken at different times of the day to\ncharacterize the telescope and find that very valuable information on the\ntelescope properties can be obtained in this manner. The results are also\nconsistent with the entrance window polarizer measurements, opening very\ninteresting possibilities for the calibration of future large-aperture solar\ntelescopes such as the ATST or the EST.", "positive": "CHILES VII: Deep Imaging for the CHILES project, a SKA prototype: Radio Astronomy is undergoing a renaissance, as the next-generation of\ninstruments provides a massive leap forward in collecting area and therefore\nraw sensitivity. However, to achieve this theoretical level of sensitivity in\nthe science data products we need to address the much more pernicious\nsystematic effects, which are the true limitation. These become all the more\nsignificant when we consider that much of the time used by survey instruments,\nsuch as the SKA, will be dedicated to deep surveys.\n CHILES is a deep HI survey of the COSMOS field, with 1,000 hours of VLA time.\nWe present our approach for creating the image cubes from the first Epoch, with\ndiscussions of the methods and quantification of the data quality from 946 to\n1420MHz -- a redshift range of 0.5 to 0. We layout the problems we had to solve\nand describe how we tackled them. These are of importance as CHILES is the\nfirst deep wideband multi-epoch HI survey and it has relevance for ongoing and\nfuture surveys.\n We focus on the accumulated systematic errors in the imaging, as the goal is\nto deliver a high-fidelity image that is only limited by the random thermal\nerrors. To understand and correct these systematic effects we ideally manage\nthem in the domain in which they arise, and that is predominately the\nvisibility domain. CHILES is a perfect test bed for many of the issues we can\nexpect for deep imaging with the SKA or ngVLA and we discuss the lessons we\nhave learned." }, { "anchor": "GRACES: Gemini remote access to CFHT ESPaDOnS Spectrograph through the\n longest astronomical fiber ever made (Experimental phase completed.): The Gemini Remote Access to CFHT ESPaDONS Spectrograph has achieved first\nlight of its experimental phase in May 2014. It successfully collected light\nfrom the Gemini North telescope and sent it through two 270 m optical fibers to\nthe the ESPaDOnS spectrograph at CFHT to deliver high-resolution spectroscopy\nacross the optical region. The fibers gave an average focal ratio degradation\nof 14% on sky, and a maximum transmittance of 85% at 800nm. GRACES achieved\ndelivering spectra with a resolution power of R = 40,000 and R = 66,000 between\n400 and 1,000 nm. It has a ~8% throughput and is sensitive to target fainter\nthan 21st mag in 1 hour. The average acquisition time of a target is around 10\nmin. This project is a great example of a productive collaboration between two\nobservatories on Maunakea that was successful due to the reciprocal involvement\nof the Gemini, CFHT, and NRC Herzberg teams, and all the staff involved closely\nor indirectly.", "positive": "Liger for Next Generation Keck Adaptive Optics: Opto-Mechanical Dewar\n for Imaging Camera and Slicer: Liger is a next generation adaptive optics (AO) fed integral field\nspectrograph (IFS) and imager for the W. M. Keck Observatory. This new\ninstrument is being designed to take advantage of the upgraded AO system\nprovided by Keck All-Sky Precision Adaptive-optics (KAPA). Liger will provide\nhigher spectral resolving power (R$\\sim$4,000-10,000), wider wavelength\ncoverage ($\\sim$0.8-2.4 $\\mu$m), and larger fields of view than any current\nIFS. We present the design and analysis for a custom-made dewar chamber for\ncharacterizing the Liger opto-mechanical system. This dewar chamber is designed\nto test and assemble the Liger imaging camera and slicer IFS components while\nbeing adaptable for future experiments. The vacuum chamber will operate below\n$10^{-5}$ Torr with a cold shield that will be kept below 90 K. The dewar test\nchamber will be mounted to an optical vibration isolation platform and further\nisolated from the cryogenic and vacuum systems with bellows. The cold head and\nvacuums will be mounted to a custom cart that will also house the electronics\nand computer that interface with the experiment. This test chamber will provide\nan efficient means of calibrating and characterizing the Liger instrument and\nperforming future experiments." }, { "anchor": "The carbon footprint of large astronomy meetings: The annual meeting of the European Astronomical Society took place in Lyon,\nFrance, in 2019, but in 2020 it was held online only due the COVID-19 pandemic.\nThe carbon footprint of the virtual meeting was roughly 3,000 times smaller\nthan the face-to-face one, providing encouragement for more ecologically minded\nconferencing.", "positive": "Pass 8: Toward the Full Realization of the Fermi-LAT Scientific\n Potential: The event selection developed for the Fermi Large Area Telescope before\nlaunch has been periodically updated to reflect the constantly improving\nknowledge of the detector and the environment in which it operates. Pass 7,\nreleased to the public in August 2011, represents the most recent major\niteration of this incremental process.\n In parallel, the LAT team has undertaken a coherent long-term effort aimed at\na radical revision of the entire event-level analysis, based on the experience\ngained in the prime phase of the mission. This includes virtually every aspect\nof the data reduction process, from the simulation of the detector to the event\nreconstruction and the background rejection. The potential improvements include\n(but are not limited to) a significant reduction in background contamination\ncoupled with an increased effective area, a better point-spread function, a\nbetter understanding of the systematic uncertainties and an extension of the\nenergy reach for the photon analysis below 100 MeV and above a few hundred GeV.\n We present an overview of the work that has been done or is ongoing and the\nprospects for the near future." }, { "anchor": "DESHIMA on ASTE: On-sky Responsivity Calibration of the Integrated\n Superconducting Spectrometer: We are developing an ultra-wideband spectroscopic instrument, DESHIMA (DEep\nSpectroscopic HIgh-redshift MApper), based on the technologies of an on-chip\nfilter-bank and Microwave Kinetic Inductance Detector (MKID) to investigate\ndusty star-burst galaxies in the distant universe at millimeter and\nsubmillimeter wavelength. An on-site experiment of DESHIMA was performed using\nthe ASTE 10-m telescope. We established a responsivity model that converts\nfrequency responses of the MKIDs to line-of-sight brightness temperature. We\nestimated two parameters of the responsivity model using a set of skydip data\ntaken under various precipitable water vapor (PWV, 0.4-3.0 mm) conditions for\neach MKID. The line-of-sight brightness temperature of sky is estimated using\nan atmospheric transmission model and the PWVs. As a result, we obtain an\naverage temperature calibration uncertainty of $1\\sigma=4$%, which is smaller\nthan other photometric biases. In addition, the average forward efficiency of\n0.88 in our responsivity model is consistent with the value expected from the\ngeometrical support structure of the telescope. We also estimate line-of-sight\nPWVs of each skydip observation using the frequency response of MKIDs, and\nconfirm the consistency with PWVs reported by the Atacama Large\nMillimeter/submillimeter Array.", "positive": "A fast algorithm for identifying Friends-of-Friends halos: We describe a simple and fast algorithm for identifying friends-of-friends\nfeatures and prove its correctness. The algorithm avoids unnecessary expensive\nneighbor queries, uses minimal memory overhead, and rejects slowdown in high\nover-density regions. We define our algorithm formally based on pair\nenumeration, a problem that has been heavily studied in fast 2-point\ncorrelation codes and our reference implementation employs a dual KD-tree\ncorrelation function code. We construct features in a hierarchical tree\nstructure, and use a splay operation to reduce the average cost of identifying\nthe root of a feature from $O[\\log L]$ to $O[1]$ ($L$ is the size of a feature)\nwithout additional memory costs. This reduces the overall time complexity of\nmerging trees from $O[L\\log L]$ to $O[L]$, reducing the number of operations\nper splay by orders of magnitude. We next introduce a pruning operation that\nskips merge operations between two fully self-connected KD-tree nodes. This\nimproves the robustness of the algorithm, reducing the number of merge\noperations in high density peaks from $O[\\delta^2]$ to $O[\\delta]$. We show\nthat for cosmological data set the algorithm eliminates more than half of merge\noperations for typically used linking lengths $b \\sim 0.2$ (relative to mean\nseparation). Furthermore, our algorithm is extremely simple and easy to\nimplement on top of an existing pair enumeration code, reusing the optimization\neffort that has been invested in fast correlation function codes." }, { "anchor": "IVOA Recommendation: VOResource: an XML Encoding Schema for Resource\n Metadata Version 1.03: This document describes an XML encoding standard for IVOA Resource Metadata,\nreferred to as VOResource. This schema is primarily intended to support\ninteroperable registries used for discovering resources; however, any\napplication that needs to describe resources may use this schema. In this\ndocument, we define the types and elements that make up the schema as\nrepresentations of metadata terms defined in the IVOA standard, Resource\nMetadata for the Virtual Observatory [Hanicsh et al. 2004]. We also describe\nthe general model for the schema and explain how it may be extended to add new\nmetadata terms and describe more specific types of resources.", "positive": "AttoSats: ChipSats, other Gram-Scale Spacecraft, and Beyond: The miniaturization of electronic and mechanical components has allowed for\nan unprecedented downscaling of spacecraft size and mass. Today, spacecraft\nwith a mass between 1 to 10 grams, AttoSats, have been developed and operated\nin space. Due to their small size, they introduce a new paradigm in spacecraft\ndesign, relying on agile development, rapid iterations, and massive redundancy.\nHowever, no systematic survey of the potential advantages and unique mission\nconcepts based on AttoSats exists. This paper explores the potential of\nAttoSats for future space missions. First, we present the state of the art of\nAttoSats. Next, we identify unique AttoSat characteristics and map them to\nfuture mission capabilities. Finally, we go beyond AttoSats and explore how\nsmart dust and nano-scale spacecraft could allow for even smaller spacecraft in\nthe milligram range: zepto- and yocto spacecraft." }, { "anchor": "Identifying diffuse spatial structures in high-energy photon lists: Data from high-energy observations are usually obtained as lists of photon\nevents. A common analysis task for such data is to identify whether diffuse\nemission exists, and to estimate its surface brightness, even in the presence\nof point sources that may be superposed. We have developed a novel\nnon-parametric event list segmentation algorithm to divide up the field of view\ninto distinct emission components. We use photon location data directly,\nwithout binning them into an image. We first construct a graph from the Voronoi\ntessellation of the observed photon locations and then grow segments using a\nnew adaptation of seeded region growing, that we call Seeded Region Growing on\nGraph, after which the overall method is named SRGonG. Starting with a set of\nseed locations, this results in an over-segmented dataset, which SRGonG then\ncoalesces using a greedy algorithm where adjacent segments are merged to\nminimize a model comparison statistic; we use the Bayesian Information\nCriterion. Using SRGonG we are able to identify point-like and diffuse extended\nsources in the data with equal facility. We validate SRGonG using simulations,\ndemonstrating that it is capable of discerning irregularly shaped low\nsurface-brightness emission structures as well as point-like sources with\nstrengths comparable to that seen in typical X-ray data. We demonstrate\nSRGonG's use on the Chandra data of the Antennae galaxies, and show that it\nsegments the complex structures appropriately.", "positive": "Time domain methods for X-ray and gamma-ray astronomy: A variety of statistical methods for understanding variability in the time\ndomain for low count rate X-ray and gamma-ray sources are explored. Variability\ncan be detected using nonparametric (Anderson-Darling and overdispersion tests)\nand parametric (sequential likelihood-based tests) tools. Once detected,\nvariability can be characterized by nonparametric (autocorrelation function,\nstructure function,wavelet analysis) and parametric (multiple change point\nmodel such as Bayesian Blocks, integer autoregressive models, C-statistic and\nPoisson regression) methods. New multidimensional variability detection\napproaches are outlined. Software packages designed for high energy data\nanalysis are deficient but tools are available in the R statistical software\nenvironment. Most of the methods presented here are not commonly used in high\nenergy astronomy." }, { "anchor": "Calibration of the instrumental polarization effects of SCExAO-CHARIS'\n spectropolarimetric mode: SCExAO at the Subaru telescope is a visible and near-infrared high-contrast\nimaging instrument employing extreme adaptive optics and coronagraphy. The\ninstrument feeds the near-infrared light (JHK) to the integral field\nspectrograph CHARIS. Recently, a Wollaston prism was added to CHARIS' optical\npath, giving CHARIS a spectropolarimetric capability that is unique among\nhigh-contrast imaging instruments. We present a detailed Mueller matrix model\ndescribing the instrumental polarization effects of the complete optical path,\nthus the telescope and instrument. The 22 wavelength bins of CHARIS provide a\nunique opportunity to investigate in detail the wavelength dependence of the\ninstrumental polarization effects. From measurements with the internal light\nsource, we find that the image derotator (K-mirror) produces strong\nwavelength-dependent crosstalk, in the worst case converting ~95% of the\nincident linear polarization to circularly polarized light that cannot be\nmeasured. Theoretical calculations show that the magnitude of the instrumental\npolarization of the telescope varies with wavelength between approximately 0.5%\nand 0.7%, and that its angle is exactly equal to the altitude angle of the\ntelescope. We plan to more accurately determine the instrumental polarization\nof the telescope with observations of a polarization standard star, and fit\nmore comprehensive physical models to all experimental data. In addition, we\nplan to integrate the complete Mueller matrix model into the existing CHARIS\npost-processing pipeline, with the aim to achieve a polarimetric accuracy of\n<0.1% in the degree of linear polarization. Our calibrations of CHARIS'\nspectropolarimetric mode will enable unique quantitative polarimetric studies\nof circumstellar disks and planetary and brown dwarf companions.", "positive": "Design and characterization of TES bolometers and SQUID readout\n electronics for a balloon-borne application: We present measurements of the electrical and thermal properties of new\narrays of bolometeric detectors that were fabricated as part of a program to\ndevelop bolometers optimized for the low photon background of the EBEX\nballoon-borne experiment. An array consists of 140 spider-web transition edge\nsensor bolometers microfabricated on a 4\" diameter silicon wafer. The designed\naverage thermal conductance of bolometers on a proto-type array is 32 pW/K, and\nmeasurements are in good agreement with this value. The measurements are taken\nwith newly developed, digital frequency domain multiplexer SQUID readout\nelectronics." }, { "anchor": "From Thread to Transcontinental Computer: Disturbing Lessons in\n Distributed Supercomputing: We describe the political and technical complications encountered during the\nastronomical CosmoGrid project. CosmoGrid is a numerical study on the formation\nof large scale structure in the universe. The simulations are challenging due\nto the enormous dynamic range in spatial and temporal coordinates, as well as\nthe enormous computer resources required. In CosmoGrid we dealt with the\ncomputational requirements by connecting up to four supercomputers via an\noptical network and make them operate as a single machine. This was\nchallenging, if only for the fact that the supercomputers of our choice are\nseparated by half the planet, as three of them are located scattered across\nEurope and fourth one is in Tokyo. The co-scheduling of multiple computers and\nthe 'gridification' of the code enabled us to achieve an efficiency of up to\n$93\\%$ for this distributed intercontinental supercomputer. In this work, we\nfind that high-performance computing on a grid can be done much more\neffectively if the sites involved are willing to be flexible about their user\npolicies, and that having facilities to provide such flexibility could be key\nto strengthening the position of the HPC community in an increasingly\nCloud-dominated computing landscape. Given that smaller computer clusters owned\nby research groups or university departments usually have flexible user\npolicies, we argue that it could be easier to instead realize distributed\nsupercomputing by combining tens, hundreds or even thousands of these\nresources.", "positive": "Polarization dOTF: on-sky focal plane wavefront sensing: The differential Optical Transfer Function (dOTF) is a focal plane wavefront\nsensing method that uses a diversity in the pupil plane to generate two\ndifferent focal plane images. The difference of their Fourier transforms\nrecovers the complex amplitude of the pupil down to the spatial scale of the\ndiversity. We produce two simultaneous PSF images with diversity using a\npolarizing filter at the edge of the telescope pupil, and a polarization camera\nto simultaneously record the two images. Here we present the first on-sky\ndemonstration of polarization dOTF at the 1.0m South African Astronomical\nObservatory telescope in Sutherland, and our attempt to validate it with\nsimultaneous Shack-Hartmann wavefront sensor images." }, { "anchor": "Testing Potential New Sites for Optical Telescopes in Australia: In coming years, Australia may find the need to build new optical telescopes\nto continue local programmes, contribute to global survey projects, and form a\nlocal multi-wavelength connection for the new radio telescopes being built. In\nthis study, we refine possible locations for a new optical telescope by\nstudying remotely sensed meteorological infrared data to ascertain expected\ncloud coverage rates across Australia, and combine these data with a Digital\nElevation Model using a Geographic Information System. We find that the best\nsites within Australia for building optical telescopes are likely to be on the\nhighest mountains in the Hamersley Range in Northwest Western Australia, while\nthe MacDonnell Ranges in the Northern Territory may also be appropriate. We\nbelieve that similar seeing values to Siding Spring should be obtainable and\nwith significantly more observing time at the identified sites. We expect to\nfind twice as many clear nights as at current telescope sites. These sites are\nthus prime locations for future on-site testing.", "positive": "An interactive, comparative and quantitative 3D visualization system for\n large-scale spectral-cube surveys using CAVE2: As the quantity and resolution of spectral-cubes from optical/infrared and\nradio surveys increase, desktop-based visualization and analysis solutions must\nadapt and evolve. Novel immersive 3D environments such as the CAVE2 at Monash\nUniversity can overcome personal computer's visualization limitations. CAVE2 is\npart advanced 2D/3D visualization space (80 stereo-capable screens providing a\ntotal of 84 million pixels) and part supercomputer ($\\sim100$ TFLOPS of\nintegrated GPU-based processing power). We present a novel visualization system\nenabling simultaneous 3D comparative visualization of $\\sim100$ spectral-cubes.\nWith CAVE2 augmented by our newly developed web-based controller interface,\nastronomers can easily organise spectral-cubes on the different display panels,\napply real-time transforms to one or many spectral cubes, and request\nquantitative information about the displayed data. We also discuss how such a\nsolution can help accelerate the discovery rate in varied research scenarios." }, { "anchor": "Efficiency Measurements and Installation of a New Grating for the OSIRIS\n Spectrograph at Keck Observatory: OSIRIS is a near-infrared integral field spectrograph operating behind the\nadaptive optics system at W. M. Keck Observatory. While OSIRIS has been a\nscientifically productive instrument to date, its sensitivity has been limited\nby a grating efficiency that is less than half of what was expected. The\nspatially averaged efficiency of the old grating, weighted by error, is\nmeasured to be 39.5 +/- 0.8 % at {\\lambda} = 1.310 {\\mu}m, with large field\ndependent variation of 11.7 % due to efficiency variation across the grating\nsurface. Working with a new vendor, we developed a more efficient and uniform\ngrating with a weighted average efficiency at {\\lambda} = 1.310 {\\mu}m of 78.0\n+/- 1.6 %, with field variation of only 2.2 %. This is close to double the\naverage efficiency and five times less variation across the field. The new\ngrating was installed in December 2012, and on- sky OSIRIS throughput shows an\naverage factor of 1.83 improvement in sensitivity between 1 and 2.4 microns. We\npresent the development history, testing, and implementation of this new\nnear-infrared grating for OSIRIS and report the comparison with the\npredecessors. The higher sensitivities are already having a large impact on\nscientific studies with OSIRIS.", "positive": "Null-stream pointing with pulsar timing arrays: Locating sources on the sky is one of the largest challenges in gravitational\nwave astronomy, owing to the omni-directional nature of gravitational wave\ndetection techniques, and the often intrinsically weak signals being observed.\nGround-based detectors can address the pointing problem by observing with a\nnetwork of detectors, effectively triangulating signal locations by observing\nthe arrival times across the network. Space-based detectors will observe\nlong-lived sources that persist while the detector moves relative to their\nlocation on the sky, using Doppler shifts of the signal to locate the sky\nposition. While these methods improve the pointing capability of a detector or\nnetwork, the angular resolution is still coarse compared to the standards one\nexpects from electromagnetic astronomy. Another technique that can be used for\nsky localization is null-stream pointing. In the case where multiple\nindependent data streams exist, a single astrophysical source of gravitational\nwaves will appear in each of the data streams. Taking the signals from multiple\ndetectors in linear combination with each other, one finds there is a two\nparameter family of coefficients that effectively null the gravitational wave\nsignal; those two parameters are the angles that define the sky location of the\nsource. This technique has been demonstrated for a network of ground-based\ninterferometric observatories, and for 6-link space interferometers. This paper\nderives and extends the null-stream pointing method to the unique case of\npulsar timing residuals. The basic method is derived and demonstrated, and the\nnecessity of using the method with multiple sub-arrays of pulsars in the pulsar\ntiming array network is considered." }, { "anchor": "A Simple Method to Test for Energy-Dependent Dispersion in High Energy\n Light-Curves of Astrophysical Sources: In this paper we discuss a simple method of testing for the presence of\nenergy-dependent dispersion in high energy data-sets. It uses the minimisation\nof the Kolmogorov distance between the cumulative distribution of two\nprobability functions as the statistical metric to estimate the magnitude of\nany spectral dispersion within transient features in a light-curve and we also\nshow that it performs well in the presence of modest energy resolutions (~20%)\ntypical of gamma-ray observations. After presenting the method in detail we\napply it to a parameterised simulated lightcurve based on the extreme VHE\ngamma-ray flare of PKS 2155-304 observed with H.E.S.S. in 2006, in order to\nillustrate its potential through the concrete example of setting constraints on\nquantum-gravity induced Lorentz invariance violation (LIV) effects. We obtain\ncomparable limits to those of the most advanced techniques used in LIV searches\napplied to similar datasets, but the present method has the advantage of being\nparticularly straightforward to use. Whilst the development of the method was\nmotivated by LIV searches, it is also applicable to other astrophysical\nsituations where energy-dependent dispersion is expected, such as spectral lags\nfrom the acceleration and cooling of particles in relativistic outflows.", "positive": "Gravity Gradient Tensor Eigendecomposition for Spacecraft Positioning: In this Note, a new approach to spacecraft positioning based on GGT inversion\nis presented. The gravity gradient tensor is initially measured in the\ngradiometer reference frame (GRF) and then transformed to the Earth-Centered\nEarth-Fixed (ECEF) frame via attitude information as well as Earth rotation\nparameters. Matrix Eigen-Decomposition is introduced to directly translate GGT\ninto position based on the fact that the eigenvalues and eigenvectors of GGT\nare simplespecific functions of spherical coordinates of the observation\nposition. without the need of an initial position. Unlike the strategy of\ninertial navigation aiding, no prediction or first guess of the spacecraft\nposition is needed. The method makes use of the J2 gravity model, and is\nsuitable for space navigation where higher frequency terrain contributions to\nthe GGT signals can be neglected." }, { "anchor": "PlanetPack: a radial-velocity time-series analysis tool facilitating\n exoplanets detection, characterization, and dynamical simulations: We present PlanetPack, a new software tool that we developed to facilitate\nand standardize the advanced analysis of radial velocity (RV) data for the goal\nof exoplanets detection, characterization, and basic dynamical $N$-body\nsimulations. PlanetPack is a command-line interpreter, that can run either in\nan interactive mode or in a batch mode of automatic script interpretation.\n Its major abilities include: (i) Advanced RV curve fitting with the proper\nmaximum-likelihood treatment of unknown RV jitter; (ii) User-friendly\nmulti-Keplerian as well as Newtonian $N$-body RV fits; (iii) Use of more\nefficient maximum-likelihood periodograms that involve the full multi-planet\nfitting (sometimes called as ``residual'' or ``recursive'' periodograms); (iv)\nEasily calculatable parametric 2D likelihood function level contours,\nreflecting the asymptotic confidence regions; (v) Fitting under some useful\nfunctional constraints is user-friendly; (vi) Basic tasks of short- and\nlong-term planetary dynamical simulation using a fast Everhart-type integrator\nbased on Gauss--Legendre spacings; (vii) Fitting the data with red noise\n(auto-correlated errors); (viii) Various analytical and numerical methods for\nthe tasks of determining the statistical significance.\n It is planned that further functionality may be added to PlanetPack in the\nfuture. During the development of this software, a lot of effort was made to\nimprove the calculational speed, especially for CPU-demanding tasks. PlanetPack\nwas written in pure C++ (standard of 1998/2003), and is expected to be\ncompilable and usable on a wide range of platforms.", "positive": "Planck pre-launch status: Low Frequency Instrument calibration and\n expected scientific performance: We give the calibration and scientific performance parameters of the Planck\nLow Frequency Instrument (LFI) measured during the ground cryogenic test\ncampaign. These parameters characterise the instrument response and constitute\nour best pre-launch knowledge of the LFI scientific performance. The LFI shows\nexcellent $1/f$ stability and rejection of instrumental systematic effects;\nmeasured noise performance shows that LFI is the most sensitive instrument of\nits kind. The set of measured calibration parameters will be updated during\nflight operations through the end of the mission." }, { "anchor": "Frequency Reference Stability and Coherence Loss in Radio Astronomy\n Interferometers Application to the SKA: The requirements on the stability of the frequency reference in the Square\nKilometre Array (SKA), as a radio astronomy interferometer, are given in terms\nof maximum accepted degree of coherence loss caused by the instability of the\nfrequency reference. In this paper we analyse the relationship between the\ncharacterisation of the instability of the frequency reference in the radio\nastronomy array and the coherence loss. The calculation of the coherence loss\nfrom the instability characterisation given by the Allan deviation is reviewed.\nSome practical aspects and limitations are analysed.", "positive": "Fortran interface layer of the framework for developing particle\n simulator FDPS: Numerical simulations based on particle methods have been widely used in\nvarious fields including astrophysics. To date, simulation softwares have been\ndeveloped by individual researchers or research groups in each field, with a\nhuge amount of time and effort, even though numerical algorithms used are very\nsimilar. To improve the situation, we have developed a framework, called FDPS,\nwhich enables researchers to easily develop massively parallel particle\nsimulation codes for arbitrary particle methods. Until version 3.0, FDPS have\nprovided API only for C++ programing language. This limitation comes from the\nfact that FDPS is developed using the template feature in C++, which is\nessential to support arbitrary data types of particle. However, there are many\nresearchers who use Fortran to develop their codes. Thus, the previous versions\nof FDPS require such people to invest much time to learn C++. This is\ninefficient. To cope with this problem, we newly developed a Fortran interface\nlayer in FDPS, which provides API for Fortran. In order to support arbitrary\ndata types of particle in Fortran, we design the Fortran interface layer as\nfollows. Based on a given derived data type in Fortran representing particle, a\nPython script provided by us automatically generates a library that manipulates\nthe C++ core part of FDPS. This library is seen as a Fortran module providing\nAPI of FDPS from the Fortran side and uses C programs internally to\ninteroperate Fortran with C++. In this way, we have overcome several technical\nissues when emulating `template' in Fortran. By using the Fortran interface,\nusers can develop all parts of their codes in Fortran. We show that the\noverhead of the Fortran interface part is sufficiently small and a code written\nin Fortran shows a performance practically identical to the one written in C++." }, { "anchor": "The Virtual Observatory Registry: In the Virtual Observatory (VO), the Registry provides the mechanism with\nwhich users and applications discover and select resources -- typically, data\nand services -- that are relevant for a particular scientific problem. Even\nthough the VO adopted technologies in particular from the bibliographic\ncommunity where available, building the Registry system involved a major\nstandardisation effort, involving about a dozen interdependent standard texts.\nThis paper discusses the server-side aspects of the standards and their\napplication, as regards the functional components (registries), the resource\nrecords in both format and content, the exchange of resource records between\nregistries (harvesting), as well as the creation and management of the\nidentifiers used in the system based on the notion of authorities. Registry\nrecord authors, registry operators or even advanced users thus receive a big\npicture serving as a guideline through the body of relevant standard texts. To\ncomplete this picture, we also mention common usage patterns and open issues as\nappropriate.", "positive": "Infrared tip-tilt sensing: on-sky experience, lessons learned and\n unsolved problems: Infrared tip-tilt sensors (IR TTSs) have been deployed on three different\nlaser guide star adaptive optics (AO) systems on three different telescopes.\nThese IR TTS benefit from the high-order loop PSF sharpening in the near\ninfrared, hence they provide a low tip-tilt residual and a good sky coverage.\nNevertheless, these IR TTS are challenging and their use in AO is limited. In\nthis paper, we outline existing IR TTS, provide on-sky performance results and\ndescribe our experience using IR TTS and along with plans for the near future.\nThe second part of the paper deals with unresolved challenges for IR TTS. These\ninclude algorithms and loop stability in the low Strehl regime, using IR TTSs\nto measure higher-order modes and guiding on multiple guide stars with\ndifferent magnitudes." }, { "anchor": "An Improved Pair Method to Probe the Dust Extinction Law: Dust extinction law is crucial to recover the intrinsic energy distribution\nof celestial objects and infer the characteristics of interstellar dust. Based\non the traditional pair method, an improved pair method is proposed to model\nthe dust extinguished spectral energy distribution (SED) of an individual star.\nInstead of the mathematically parameterizing extinction curves, the extinction\ncurves in this work are directly from the silicate-graphite dust model, so that\nthe dust extinction law can be obtained and the dust properties can be analyzed\nsimultaneously. The ATLAS9 stellar model atmosphere is adopted for the\nintrinsic SEDs in this work, while the silicate-graphite dust model with a dust\nsize distribution of $dn/da \\sim a^{-\\alpha}{\\rm exp}(-a/a_c),~0.005 < a <\n5~\\mu{\\rm m}$ for each component is adopted for the model extinction curves.\nOne typical extinction tracer in the dense region (V410 Anon9) and one in the\ndiffuse region (Cyg OB2 \\#12) of the MW are chosen to test the reliability and\nthe practicability of the improved pair method in different stellar\nenvironments. The results are consistent with their interstellar environments\nand are in agreement with the previous observations and studies, which prove\nthat the improved pair method is effective and applicable in different stellar\nenvironments. In addition to the reliable extinction results, the derived\nparameters in the dust model can be used to analyze the dust properties, which\ncannot be achieved by other methods with the mathematical extinction models.\nWith the improved pair method, the stellar parameters can also be inferred and\nthe extinction law beyond the wavelengths of observed data can be predicted\nbased on the dust model as well.", "positive": "A geometric delay model for Space VLBI: A relativistic delay model for space very long baseline interferometry\n(hereafter SVLBI) observation of sources at infinite distance is derived. In\nSVLBI, where one station is on a spacecraft, the orbiting station's maximum\nspeed in an elliptical Earth orbit is much bigger than the ground VLBI (here\nafter GVLBI), leading to a higher delay rate . The delay models inside the VLBI\ncorrelators are usually expressed as fifth-order polynomials in time that good\nfor a limited time interval, which are evaluated by the correlator firmware and\ntrack the interferometer delays over a limited time interval. The higher SVLBI\ndelay rate requires more accurate polynomial fitting and evalution, more\nfrequent model updates." }, { "anchor": "An improved analysis framework for axion dark matter searches: In experiments searching for axionic dark matter, the use of the standard\nthreshold-based data analysis discards valuable information. We present a\nBayesian analysis framework that builds on an existing processing protocol to\nextract more information from the data of coherent axion detectors such as\noperating haloscopes. The analysis avoids logical subtleties that accompany the\nstandard analysis framework and enables greater experimental flexibility on\nfuture data runs. Performing this analysis on the existing data from the\nHAYSTAC experiment, we find improved constraints on the axion-photon coupling\n$g_\\gamma$ while also identifying the most promising regions of parameter space\nwithin the $23.15$--$24.0$ $\\mu$eV mass range. A comparison with the standard\nthreshold analysis suggests a $36\\%$ improvement in scan rate from our\nanalysis, demonstrating the utility of this framework for future axion\nhaloscope analyses.", "positive": "Prototype 9.7 m Schwarzschild-Couder telescope for the Cherenkov\n Telescope Array: status of the optical system: The Cherenkov Telescope Array (CTA) is an international project for a\nnext-generation ground-based gamma ray observatory, aiming to improve on the\nsensitivity of current-generation experiments by an order of magnitude and\nprovide energy coverage from 30 GeV to more than 300 TeV. The 9.7m\nSchwarzschild-Couder (SC) candidate medium-size telescope for CTA exploits a\nnovel aplanatic two-mirror optical design that provides a large field of view\nof 8 degrees and substantially improves the off-axis performance giving better\nangular resolution across all of the field of view with respect to\nsingle-mirror telescopes. The realization of the SC optical design implies the\nchallenging production of large aspherical mirrors accompanied by a\nsubmillimeter-precision custom alignment system. In this contribution we report\non the status of the implementation of the optical system on a prototype 9.7 m\nSC telescope located at the Fred Lawrence Whipple Observatory in southern\nArizona." }, { "anchor": "The list of tantalum lines for wavelengths calibration of the Hamilton\n echelle-spectrograph: We present solution of the problem of wavelength calibration for Hamilton\nEchelle spectrograph using hollow cathode lamp, which was operated at Lick\nObservatory Shane telescope before June 9, 2011. The spectrum of the lamp\nclaimed to be thorium-argon, contains, in addition to the lines of thorium and\nargon, a number of the unrecognized lines identified by us with tantalum. Using\natomic data for measured lines of tantalum and thorium, we estimated the\ntemperature of the gas in the lamp as T=3120+/-60 K. From the atomic line\ndatabase VALD3 we selected all lines of TaI and TaII which can be seen in the\nspectrum of the lamp and compiled a list for the use in the processing of\nspectral observations. We note a limitation of the accuracy of calibration due\nto the influence of the hyperfine line splitting.", "positive": "Phase Quantization Study of Spatial Light Modulator for Extreme High\n contrast Imaging: Direct imaging of exoplanets by reflected starlight is extremely challenging\ndue to the large luminosity ratio to the primary star. Wave-front control is a\ncritical technique to attenuate the speckle noise in order to achieve an\nextremely high contrast. We present a phase quantization study of a spatial\nlight modulator for wave front control to meet the contrast requirement of\ndetection of a terrestrial planet in the habitable zone of a solar-type star.\nWe perform the numerical simulation by employing the SLM with different phase\naccuracy and actuator numbers, which are related to the achievable contrast. We\nuse an optimization algorithm to solve the quantization problems that is\nmatched to the controllable phase step of the SLM. Two optical configurations\nare discussed with the SLM located before and after the coronagraph focal plane\nmask. The simulation result has constrained the specification for SLM phase\naccuracy in the above two optical configurations. Finally, we have demonstrated\nthat a SLM with more actuators can deliver a competitive contrast performance\nto that by using a deformable mirror." }, { "anchor": "CASSIS: The Cornell Atlas of Spitzer/Infrared Spectrograph Sources. II.\n High-resolution observations: The Infrared Spectrograph (IRS) on board the Spitzer Space Telescope observed\nabout 15,000 objects during the cryogenic mission lifetime. Observations\nprovided low-resolution (R~60-127) spectra over ~5-38um and high-resolution\n(R~600) spectra over ~10-37um. The Cornell Atlas of Spitzer/IRS Sources\n(CASSIS) was created to provide publishable quality spectra to the community.\nLow-resolution spectra have been available in CASSIS since 2011, and we present\nhere the addition of the high-resolution spectra. The high-resolution\nobservations represent approximately one third of all staring observations\nperformed with the IRS instrument. While low-resolution observations are\nadapted to faint objects and/or broad spectral features (e.g., dust continuum,\nmolecular bands), high-resolution observations allow more accurate measurements\nof narrow features (e.g., ionic emission lines) as well as a better sampling of\nthe spectral profile of various features. Given the narrow aperture of the two\nhigh-resolution modules, cosmic ray hits and spurious features usually plague\nthe spectra. Our pipeline is designed to minimize these effects through various\nimprovements. A super sampled point-spread function was created in order to\nenable the optimal extraction in addition to the full aperture extraction. The\npipeline selects the best extraction method based on the spatial extent of the\nobject. For unresolved sources, the optimal extraction provides a significant\nimprovement in signal-to-noise ratio over a full aperture extraction. We have\ndeveloped several techniques for optimal extraction, including a differential\nmethod that eliminates low-level rogue pixels (even when no dedicated\nbackground observation was performed). The updated CASSIS repository now\nincludes all the spectra ever taken by the IRS, with the exception of mapping\nobservations.", "positive": "Performance of the PRAXyS X-ray Polarimeter: The performance of the Time Projection Chamber (TPC) polarimeter for the\nPolarimeter for Relativistic Astrophysical X-ray Sources (PRAXyS) Small\nExplorer was evaluated using polarized and unpolarized X-ray sources. The\nPRAXyS mission will enable exploration of the universe through X-ray\npolarimetry in the 2-10 keV energy band. We carried out performance tests of\nthe polarimeter at the Brookhaven National Laboratory, National Synchrotron\nLight Source (BNL-NSLS) and at NASA's Goddard Space Flight Center. The\npolarimeter was tested with linearly polarized, monochromatic X-rays at 11\ndifferent energies between 2.5 and 8.0 keV. At maximum sensitivity, the\nmeasured modulation factors at 2.7, 4.5 and 8.0 keV are 27%, 43% and 59%,\nrespectively and the measured angle of polarization is consistent with the\nexpected value at all energies. Measurements with a broadband, unpolarized\nX-ray source placed a limit of less than 1% on false polarization in the PRAXyS\npolarimeter." }, { "anchor": "Cornerstone: Octree Construction Algorithms for Scalable Particle\n Simulations: This paper presents an octree construction method, called Cornerstone, that\nfacilitates global domain decomposition and interactions between particles in\nmesh-free numerical simulations. Our method is based on algorithms developed\nfor 3D computer graphics, which we extend to distributed high performance\ncomputing (HPC) systems. Cornerstone yields global and locally essential\noctrees and is able to operate on all levels of tree hierarchies in parallel.\nThe resulting octrees are suitable for supporting the computation of various\nkinds of short and long range interactions in N-body methods, such as\nBarnes-Hut and the Fast Multipole Method (FMM). While we provide a CPU\nimplementation, Cornerstone may run entirely on GPUs. This results in\nsignificantly faster tree construction compared to execution on CPUs and serves\nas a powerful building block for the design of simulation codes that move\nbeyond an offloading approach, where only numerically intensive tasks are\ndispatched to GPUs. With data residing exclusively in GPU memory, Cornerstone\neliminates data movements between CPUs and GPUs. As an example, we employ\nCornerstone to generate locally essential octrees for a Barnes-Hut treecode\nrunning on almost the full LUMI-G system with up to 8 trillion particles.", "positive": "Wavefront tolerances of space-based segmented telescopes at very high\n contrast: Experimental validation: Context: The detection and characterization of Earth-like exoplanets\n(exoEarths) from space requires exquisite wavefront stability at contrast\nlevels of $10^{-10}$. On segmented telescopes in particular, aberrations\ninduced by cophasing errors lead to a light leakage through the coronagraph,\ndeteriorating the imaging performance. These need to be limited in order to\nfacilitate the direct imaging of exoEarths. Aims: We perform a laboratory\nvalidation of an analytical tolerancing model that allows us to determine\nwavefront error requirements in the $10^{-6} - 10^{-8}$ contrast regime, for a\nsegmented pupil with a classical Lyot coronagraph. We intend to compare the\nresults to simulations, and we aim to establish an error budget for the\nsegmented mirror on the High-contrast imager for Complex Aperture Telescopes\n(HiCAT) testbed. Methods: We use the Pair-based Analytical model for Segmented\nTelescope Imaging from Space (PASTIS) to measure a contrast influence matrix of\na real high contrast instrument, and use an analytical model inversion to\ncalculate per-segment wavefront error tolerances. We validate these tolerances\non the HiCAT testbed by measuring the contrast response of segmented mirror\nstates that follow these requirements. Results: The experimentally measured\noptical influence matrix is successfully measured on the HiCAT testbed, and we\nderive individual segment tolerances from it that correctly yield the targeted\ncontrast levels. Further, the analytical expressions that predict a contrast\nmean and variance from a given segment covariance matrix are confirmed\nexperimentally." }, { "anchor": "An update on site search activities for SWGO: The Southern Wide-field Gamma-ray Observatory (SWGO) is a project by\nscientists and engineers from 14 countries and 78 institutions to design and\nbuild the first wide-field, ground-based gamma-ray observatory in the Southern\nHemisphere, with high duty cycle and covering an energy range rom hundreds of\nGeV to the PeV scale. The observatory will cover the Southern sky and aims to\nmap the Galaxy's large-scale emission, as well as detecting transient and\nvariable phenomena. The host sites under consideration are at a minimum\naltitude of 4400 m.a.s.l. and comprise two types: flat plateaus of at least 1\nkm$^{2}$ for the installation of an array of tank-based water Cherenkov\ndetectors (WCD), or large natural lakes for the direct deployment of WCD units.\nFour South American countries proposed excellent sites to host the observatory\nmeeting these requirements. Argentina proposed two locations in the Salta\nprovince, Bolivia presented one site in Chacaltaya, Chile two locations within\nthe Atacama Astronomical Park, and Peru two ground-based locations in the\nArequipa district as well as lakes in the Cuzco region. The SWGO collaboration\nis currently conducting a site characterization study, gathering all the\nnecessary information for site shortlisting and final site selection by the end\nof 2023. The process has reached the shortlisting phase, in which primary and\nbackup sites for each country have been identified. The primary sites were\nvisited by a team of experts from the collaboration, to investigate and\nvalidate the proposed site characteristics. Here we present an update on these\nsite selection activities.", "positive": "Imaging Polarimeter for a Sub-MeV Gamma-Ray All-Sky Survey using an\n Electron-Tracking Compton Camera: X-ray and gamma-ray polarimetry is a promising tool to study the geometry and\nthe magnetic configuration of various celestial objects, such as binary black\nholes or gamma-ray bursts (GRBs). However, statistically significant\npolarizations have been detected in few of the brightest objects. Even though\nfuture polarimeters using X-ray telescopes are expected to observe weak\npersistent sources, there are no effective approaches to survey transient and\nserendipitous sources with a wide field of view (FoV). Here we present an\nelectron-tracking Compton camera (ETCC) as a highly-sensitive gamma-ray imaging\npolarimeter. The ETCC provides powerful background rejection and a high\nmodulation factor over a FoV of up to 2$\\pi$ sr thanks to its excellent imaging\nbased on a well-defined point spread function. Importantly, we demonstrated for\nthe first time the stability of the modulation factor under realistic\nconditions of off-axis incidence and huge backgrounds using the SPring-8\npolarized X-ray beam. The measured modulation factor of the ETCC was 0.65 $\\pm$\n0.01 at 150 keV for an off-axis incidence with an oblique angle of 30$^\\circ$\nand was not degraded compared to the 0.58 $\\pm$ 0.02 at 130 keV for on-axis\nincidence. These measured results are consistent with the simulation results.\nConsequently, we found that the satellite-ETCC proposed in Tanimori et al.\n(2015) would provide all-sky surveys of weak persistent sources of 13 mCrab\nwith 10% polarization for a 10$^{7}$ s exposure and over 20 GRBs down to a\n$6\\times10^{-6}$ erg cm$^{-2}$ fluence and 10% polarization during a one-year\nobservation." }, { "anchor": "PLC-controlled cryostats for the BlackGEM and MeerLICHT detectors: BlackGEM (BG) is an array of telescopes, currently under development at the\nRadboud University Nijmegen and at NOVA. It targets the detection of the\noptical counterparts of gravitational waves. The first 3 BG telescopes are\nplanned to be installed in 2018 at the La Silla observatory. A single prototype\ntelescope, named MeerLICHT, will already be commissioned early 2017 in\nSutherland to provide an optical complement for the MeerKAT radio array. The BG\narray consists of, initially, a set of 3 robotic 65-cm wide-field telescopes.\nEach telescope is equipped with a single STA1600 CCD detector with 10.5k x\n10.5k 9-mum pixels that covers a 2.7 square degrees field of view. The\ncryostats for housing these detectors are developed and built at the KU Leuven\nUniversity. The operational model of BG requires long periods of reliable\nands-off operation. Therefore, we designed the cryostats for long vacuum hold\ntime and we make use of a closed-cycle cooling system, based on Polycold PCC\nJoule-Thomson coolers. A single programmable logic controller (PLC) controls\nthe cryogenic systems of several BG telescopes simultaneously, resulting in a\nhighly reliable, cost-efficient and maintenance-friendly system. PLC-based\ncryostat control offers some distinct advantages, especially for a robotic\nfacility. Apart of temperature monitoring and control, the PLC also monitors\nthe vacuum quality, the power supply and the status of the PCC coolers\n(compressor power consumption and temperature, pressure in the gas lines,\netc.). Furthermore, it provides an alarming system and safe and reproducible\nprocedures for automatic cool down and warm up. The communication between PLC\nand higher-level software takes place via the OPC-UA protocol, offering a\nsimple to implement, yet very powerful interface. Finally, a touch-panel\ndisplay on the PLC provides the operator with a user-friendly and robust\ntechnical interface.", "positive": "Simulating image coaddition with the Nancy Grace Roman Space Telescope:\n II. Analysis of the simulated images and implications for weak lensing: One challenge for applying current weak lensing analysis tools to the Nancy\nGrace Roman Space Telescope is that individual images will be undersampled. Our\ncompanion paper presented an initial application of Imcom - an algorithm that\nbuilds an optimal mapping from input to output pixels to reconstruct a fully\nsampled combined image - on the Roman image simulations. In this paper, we\nmeasure the output noise power spectra, identify the sources of the major\nfeatures in the power spectra, and show that simple analytic models that ignore\nsampling effects underestimate the power spectra of the coadded noise images.\nWe compute the moments of both idealized injected stars and fully simulated\nstars in the coadded images, and their 1- and 2-point statistics. We show that\nthe idealized injected stars have root-mean-square ellipticity errors (1 - 6) x\n10-4 per component depending on the band; the correlation functions are >= 2\norders of magnitude below requirements, indicating that the image combination\nstep itself is using a small fraction of the overall Roman 2nd moment error\nbudget, although the 4th moments are larger and warrant further investigation.\nThe stars in the simulated sky images, which include blending and chromaticity\neffects, have correlation functions near the requirement level (and below the\nrequirement level in a wide-band image constructed by stacking all 4 filters).\nWe evaluate the noise-induced biases in the ellipticities of injected stars,\nand explain the resulting trends with an analytical model. We conclude by\nenumerating the next steps in developing an image coaddition pipeline for\nRoman." }, { "anchor": "ASTENA: a mission concept for a deep study of the transient gamma-ray\n sky and for nuclear astrophysics: Gamma-ray astronomy is a branch whose potential has not yet been fully\nexploited. The observations of elemental and isotopic abundances in supernova\n(SN) explosions are key probes not only of the stellar structure and evolution\nbut also for understanding the physics that makes Type-Ia SNe as standard\ncandles for the study of the Universe expansion properties. In spite of its\ncrucial role, nuclear astrophysics remains a poorly explored field mainly for\nthe typical emission lines intensity which are vanishing small and requires\nvery high sensitivities of the telescopes. Furthermore, in spite that the\nGalactic bulge-dominated intensity of positron annihilation line at 511 keV has\nbeen measured, its origin is still a mystery due to the poor angular resolution\nand insufficient sensitivity of the commonly employed instrumentation in the\nsub-MeV energy domain. To answer these scientific issues a jump in sensitivity\nand angular resolution with respect to the present instrumentation is required.\nConceived within the EU project AHEAD, a new high energy mission, capable of\ntackling the previously mentioned topics, has been proposed. This concept of\nmission named ASTENA (Advanced Surveyor of Transient Events and Nuclear\nAstrophysics), includes two instruments: a Wide Field Monitor with Imaging and\nSpectroscopic (WFM-IS, 2 keV - 20 MeV) capabilities and a Narrow Field\nTelescope (NFT, 50 - 700 keV). Thanks to the combination of angular resolution,\nsensitivity and large FoV, ASTENA will be a breakthrough in the hard X and soft\ngamma--ray energy band, also enabling polarimetry in this energy band. In this\ntalk the science goals of the mission are discussed, the payload configuration\nis described and expected performances in observing key targets are shown.", "positive": "DSA-10: A Prototype Array for Localizing Fast Radio Bursts: The Deep Synoptic Array 10 dish prototype is an instrument designed to detect\nand localise fast radio bursts with arcsecond accuracy in real time. Deployed\nat Owens Valley Radio Observatory, it consists of ten 4.5m diameter dishes,\nequipped with a 250MHz bandwidth dual polarisation receiver, centered at\n1.4GHz. The 20 input signals are digitised and field programmable gate arrays\nare used to transform the data to the frequency domain and transmit it over\nethernet. A series of computer servers buffer both raw data samples and perform\na real time search for fast radio bursts on the incoherent sum of all inputs.\nIf a pulse is detected, the raw data surrounding the pulse is written to disk\nfor coherent processing and imaging. The prototype system was operational from\nJune 2017 - February 2018 conducting a drift scan search. Giant pulses from the\nCrab pulsar were used to test the detection and imaging pipelines. The 10-dish\nprototype system was brought online again in March 2019, and will gradually be\nreplaced with the new DSA-110, a 110-dish system, over the next two years to\nimprove sensitivity and localisation accuracy." }, { "anchor": "Multi-scale three-dimensional visualization of emission, scattering and\n absorption in active galactic nuclei using Virtual Observatories tools: Whether aimed for the study of the planetary systems, the distribution of the\nstars in the galaxies or the formation of the large-scale structures in the\nUniverse, the sizes of numerical simulations are becoming increasingly\nimportant in terms of their virtual volumes and computer memories. The\nvisualization of the data becomes more complicated with the requirement of the\nexposition of the large number of data points. In order to lighten such burden,\nVirtual Observatories (VO) have been developed and are now essential tools in\nastronomy to share existing data, for visualization and for data analysis.\nUsing a software, currently being developed at the Centre de Donn\\'ees de\nStrasbourg (CDS) jointly with the Astronomical Observatory of Strasbourg, we\nshow how three-dimensional radiative transfer simulations of active galactic\nnuclei (AGN) can be visualized in order to extract new information. The ability\nto zoom over ten orders of magnitude and to journey inside/between the multiple\nscattering regions allows to identify where emission, scattering, and\nabsorption truly take place. Among all the new possibilities offered by the\nsoftware, it is possible to test the single-scattering hypothesis or evaluate\nthe impact of fragmentation onto the propagation of light echoes within the\nbroad line region (BLR) or the circumnuclear region (torus).", "positive": "FAIR approach for Low Frequency Radio Astronomy: The Open Science paradigm and the FAIR principles (Findable, Accessible,\nInteroperable, Reusable) are aiming at fostering scientific return, and\nreinforcing the trust in science production. The MASER (Measuring, Analysing\nand Simulating Emissions in the Radio range) services implement Open Science\nthrough a series of existing solutions that have been put together, only adding\nnew pieces where needed. It is a \"science ready\" toolbox dedicated to\ntime-domain low frequency radioastronomy, which data products mostly covers\nsolar and planetary observations.\n MASER solutions are based on IVOA protocols for data discovery, on IHDEA\ntools for data exploration, and on a dedicated format developed by MASER for\nthe temporal-spectral annotations. The service also proposes a data repository\nfor sharing data collections, catalogues and associated documentation, as well\nas supplementary materials associated to papers. Each collection is managed\nthrough a Data Management Plan, which purpose is two-fold: supporting the\nprovider for managing the collection content; and supporting the data centre\nfor resource management. Each product of the repository is citable with a DOI,\nand the landing page contains web semantics annotations (using schema.org)" }, { "anchor": "Radiation hardness studies of InGaAs and Si photodiodes at 30, 52, & 98\n MeV and fluences to 5x10^11 protons/cm^2: Here we report the results of an investigation into the effects of ionizing\nradiation on commercial-off-the-shelf InGaAs and Si photodiodes. The\nphotodiodes were exposed to 30, 52, and 98 MeV protons with fluences ranging\nfrom 10^8 - 5x10^11 protons/cm^2 at the Indiana University Cyclotron Facility.\nWe tested the photodiodes for changes to their dark current and their relative\nresponsivity as a function of wavelength. The Si photodiodes showed increasing\ndamage to their responsivity with increasing fluence; the InGaAs photodiodes\nshowed significantly increased dark current as the fluence increased. In\naddition, we monitored the absolute responsivity of the InGaAs photodiodes over\ntheir entire bandpass. Our measurements showed no evidence for broadband\ndegradation or graying of the response at the fluences tested. All measurements\nin this investigation were made relative to detectors traceable to NIST\nstandards.", "positive": "The SIRIUS Mixed analog-digital ASIC developed for the LOFT LAD and WFM\n instruments: We report on the development and characterization of the low-noise, low\npower, mixed analog-digital SIRIUS ASICs for both the LAD and WFM X-ray\ninstruments of LOFT. The ASICs we developed are reading out large area silicon\ndrift detectors (SDD). Stringent requirements in terms of noise (ENC of 17 e-\nto achieve an energy resolution on the LAD of 200 eV FWHM at 6 keV) and power\nconsumption (650 {\\mu}W per channel) were basis for the ASICs design. These\nSIRIUS ASICs are developed to match SDD detectors characteristics: 16 channels\nASICs adapted for the LAD (970 microns pitch) and 64 channels for the WFM (145\nmicrons pitch) will be fabricated. The ASICs were developed with the 180nm\nmixed technology of TSMC." }, { "anchor": "Building a scalable global data processing pipeline for large\n astronomical photometric datasets: Astronomical photometry is the science of measuring the flux of a celestial\nobject. Since its introduction, the CCD has been the principle method of\nmeasuring flux to calculate the apparent magnitude of an object. Each CCD image\ntaken must go through a process of cleaning and calibration prior to its use.\nAs the number of research telescopes increases the overall computing resources\nrequired for image processing also increases. Existing processing techniques\nare primarily sequential in nature, requiring increasingly powerful servers,\nfaster disks and faster networks to process data. Existing High Performance\nComputing solutions involving high capacity data centres are complex in design\nand expensive to maintain, while providing resources primarily to high profile\nscience projects. This research describes three distributed pipeline\narchitectures, a virtualised cloud based IRAF, the Astronomical Compute Node\n(ACN), a private cloud based pipeline, and NIMBUS, a globally distributed\nsystem. The ACN pipeline processed data at a rate of 4 Terabytes per day\ndemonstrating data compression and upload to a central cloud storage service at\na rate faster than data generation. The primary contribution of this research\nis NIMBUS, which is rapidly scalable, resilient to failure and capable of\nprocessing CCD image data at a rate of hundreds of Terabytes per day. This\npipeline is implemented using a decentralised web queue to control the\ncompression of data, uploading of data to distributed web servers, and creating\nweb messages to identify the location of the data. Using distributed web queue\nmessages, images are downloaded by computing resources distributed around the\nglobe. Rigorous experimental evidence is presented verifying the horizontal\nscalability of the system which has demonstrated a processing rate of 192\nTerabytes per day with clear indications that higher processing rates are\npossible.", "positive": "Prototype Schwarzschild-Couder Telescope for the Cherenkov Telescope\n Array: Commissioning Status of the Optical System: The Cherenkov Telescope Array (CTA), with more than 100 telescopes, will be\nthe largest ever ground-based gamma-ray observatory and is expected to greatly\nimprove on both gamma-ray detection sensitivity and energy coverage compared to\ncurrent-generation detectors. The 9.7-m Schwarzschild-Couder telescope (SCT) is\none of the two candidates for the medium size telescope (MST) design for CTA.\nThe novel aplanatic dual-mirror SCT design offers a wide field-of-view with a\ncompact plate scale, allowing for a large number of camera pixels that improves\nthe angular resolution and reduce the night sky background noise per pixel\ncompared to the traditional single-mirror Davies-Cotton (DC) design of\nground-based gamma-ray telescopes. The production, installation, and the\nalignment of the segmented aspherical mirrors are the main challenges for the\nrealization of the SCT optical system. In this contribution, we report on the\ncommissioning status, the alignment procedures, and initial alignment results\nduring the initial commissioning phase of the optical system of the prototype\nSCT." }, { "anchor": "How well can Charge Transfer Inefficiency be corrected? A parameter\n sensitivity study for iterative correction: Radiation damage to space-based Charge-Coupled Device (CCD) detectors creates\ndefects which result in an increasing Charge Transfer Inefficiency (CTI) that\ncauses spurious image trailing. Most of the trailing can be corrected during\npost-processing, by modelling the charge trapping and moving electrons back to\nwhere they belong. However, such correction is not perfect -- and damage is\ncontinuing to accumulate in orbit. To aid future development, we quantify the\nlimitations of current approaches, and determine where imperfect knowledge of\nmodel parameters most degrade measurements of photometry and morphology. As a\nconcrete application, we simulate $1.5\\times10^{9}$ \"worst case\" galaxy and\n$1.5\\times10^{8}$ star images to test the performance of the Euclid visual\ninstrument detectors. There are two separable challenges: If the model used to\ncorrect CTI is perfectly the same as that used to add CTI, $99.68$ % of\nspurious ellipticity is corrected in our setup. This is because readout noise\nis not subject to CTI, but gets over-corrected during correction. Second, if we\nassume the first issue to be solved, knowledge of the charge trap density\nwithin $\\Delta\\rho/\\rho\\!=\\!(0.0272\\pm0.0005)$ %, and the characteristic\nrelease time of the dominant species to be known within\n$\\Delta\\tau/\\tau\\!=\\!(0.0400\\pm0.0004)$ % will be required. This work presents\nthe next level of definition of in-orbit CTI calibration procedures for Euclid.", "positive": "Light Yield in DarkSide-10: a Prototype Two-phase Liquid Argon TPC for\n Dark Matter Searches: As part of the DarkSide program of direct dark matter searches using liquid\nargon TPCs, a prototype detector with an active volume containing 10 kg of\nliquid argon, DarkSide-10, was built and operated underground in the Gran Sasso\nNational Laboratory in Italy. A critically important parameter for such devices\nis the scintillation light yield, as photon statistics limits the rejection of\nelectron-recoil backgrounds by pulse shape discrimination. We have measured the\nlight yield of DarkSide-10 using the readily-identifiable full-absorption peaks\nfrom gamma ray sources combined with single-photoelectron calibrations using\nlow-occupancy laser pulses. For gamma lines of energies in the range 122-1275\nkeV, we get consistent light yields averaging 8.887+-0.003(stat)+-0.444(sys)\np.e./keVee. With additional purification, the light yield measured at 511 keV\nincreased to 9.142+-0.006(stat) p.e./keVee." }, { "anchor": "COSMIC: An Ethernet-based Commensal, Multimode Digital Backend on the\n Karl G. Jansky Very Large Array for the Search for Extraterrestrial\n Intelligence: The primary goal of the search for extraterrestrial intelligence (SETI) is to\ngain an understanding of the prevalence of technologically advanced beings\n(organic or inorganic) in the Galaxy. One way to approach this is to look for\ntechnosignatures: remotely detectable indicators of technology, such as\ntemporal or spectral electromagnetic emissions consistent with an artificial\nsource. With the new Commensal Open-Source Multimode Interferometer Cluster\n(COSMIC) digital backend on the Karl G. Jansky Very Large Array (VLA), we aim\nto conduct a search for technosignatures that is significantly more\ncomprehensive, more sensitive, and more efficient than previously attempted.\nThe COSMIC system is currently operational on the VLA, recording data, and\ndesigned with the flexibility to provide user-requested modes. This paper\ndescribes the hardware system design, the current software pipeline, and plans\nfor future development.", "positive": "Artificial neural networks for selection of pulsar candidates from the\n radio continuum surveys: Pulsar search with time-domain observation is very computationally expensive\nand data volume will be enormous with the next generation telescopes such as\nthe Square Kilometre Array. We apply artificial neural networks (ANNs), a\nmachine learning method, for efficient selection of pulsar candidates from\nradio continuum surveys, which are much cheaper than time-domain observation.\nWith observed quantities such as radio fluxes, sky position and compactness as\ninputs, our ANNs output the \"score\" that indicates the degree of likeliness of\nan object to be a pulsar. We demonstrate ANNs based on existing survey data by\nthe TIFR GMRT Sky Survey (TGSS) and the NRAO VLA Sky Survey (NVSS) and test\ntheir performance. Precision, which is the ratio of the number of pulsars\nclassified correctly as pulsars to that of any objects classified as pulsars,\nis about 96$\\%$. Finally, we apply the trained ANNs to unidentified radio\nsources and our fiducial ANN with five inputs (the galactic longitude and\nlatitude, the TGSS and NVSS fluxes and compactness) generates 2,436 pulsar\ncandidates from 456,866 unidentified radio sources. These candidates need to be\nconfirmed if they are truly pulsars by time-domain observations. More\ninformation such as polarization will narrow the candidates down further." }, { "anchor": "AMBRE: A Compact Instrument to Measure Thermal Ions, Electrons and\n Electrostatic Charging Onboard Spacecraft: The Active Monitor Box of Electrostatic Risks (AMBER) is a double-head\nthermal electron and ion electrostatic analyzer (energy range 0-30 keV) that\nwas launched onboard the Jason-3 spacecraft in 2016. The next generation AMBER\ninstrument, for which a first prototype was developed and then calibrated at\nthe end of 2017, constitutes a significant evolution that is based on a single\nhead to measure both species alternatively. The instrument developments focused\non several new subsystems (front-end electronics, high-voltage electronics,\nmechanical design) that permit to reduce instrument resources down to ~ 1 kg\nand 1.5 W. AMBER is designed as a generic radiation monitor with a twofold\npurpose: (1) measure magnetospheric thermal ion and electron populations in the\nrange 0-35 keV, with significant scientific potential (e.g., plasmasphere, ring\ncurrent, plasma sheet), and (2) monitor spacecraft electrostatic charging and\nthe plasma populations responsible for it, for electromagnetic cleanliness and\noperational purposes.", "positive": "About the atomic and molecular databases in the planetary community -- A\n contribution in the Laboratory Astrophysics Data WG IAU 2022 GA session: This paper corresponds to an invited oral contribution to the session 5A\norganised by the IAU inter-commission B2-B5 working group (WG) \"Laboratory\nAstrophysics Data Compilation, Validation and Standardization: from the\nLaboratory to FAIR usage in the Astronomical Community\" at the IAU 2022 General\nAssembly (GA). This WG provides a platform where to discuss the Findability,\nAccessibility,Interoperability, Reuse (FAIR) usage of laboratory Atomic and\nMolecular (A&M) data in astronomy and astrophysics.\n A&M data play a key role in the understanding of the physics and chemistry of\nprocesses in several research topics, including planetary science and\ninterdisciplinary research in particular the atmospheres of planets and\nplanetary explorations, etc. Databases, compilation of spectroscopic\nparameters, and facility tools are used by computer codes to interpret\nspectroscopic observations and simulate them. In this talk I presented existing\nA&M databases of interest to the planetary community focusing on access,\norganisation, infrastructures, limitations and issues, etc." }, { "anchor": "The h-index in Australian Astronomy: The Hirsch (2005) h-index is now widely used as a metric to compare\nindividual researchers. To evaluate it in the context of Australian Astronomy,\nthe h-index for every member of the Astronomical Society of Australia (ASA) is\nfound using NASA's Astrophysics Data System Bibliographic Services (ADS).\nPercentiles of the h-index distribution are detailed for a variety of\ncategories of ASA members, including students. This enables a list of the top\nten Australian researchers by h-index to be produced. These top researchers\nhave h-index values in the range 53