Sazuna/UAT_keywords huggingface dataset:
Regularized Maximum Likelihood Image Synthesis and Validation for ALMA Continuum Observations of Protoplanetary Disks. Regularized Maximum Likelihood (RML) techniques are a class of image synthesis methods that achieve better angular resolution and image fidelity than traditional methods like CLEAN for sub-mm interferometric observations. To identify best practices for RML imaging, we used the GPU-accelerated open source Python package MPoL, a machine learning-based RML approach, to explore the influence of common RML regularizers (maximum entropy, sparsity, total variation, and total squared variation) on images reconstructed from real and synthetic Atacama Large millimeter/submillimeter Array (ALMA) continuum observations of protoplanetary disks. We tested two different cross-validation (CV) procedures to characterize their performance and determine optimal prior strengths, and found that CV over a coarse grid of regularization strengths easily identifies a range of models with comparably strong predictive power. To evaluate the performance of RML techniques against a ground truth image, we used MPoL on a synthetic protoplanetary disk data set and found that RML methods successfully resolve structures at fine spatial scales present in the original simulation. We used ALMA DSHARP observations of the protoplanetary disk around HD 143006 to compare the performance of MPoL and CLEAN, finding that RML imaging improved the spatial resolution of the image by up to a factor of 3 without sacrificing sensitivity. We provide general recommendations for building an RML workflow for image synthesis of ALMA protoplanetary disk observations, including effective use of CV. Using these techniques to improve the imaging resolution of protoplanetary disk observations will enable new science, including the detection of protoplanets embedded in disks.

Keywords: Open source software, Deconvolution, Protoplanetary disks, Submillimeter astronomy, Radio interferometry
Research on Calibration Method of off-axis Closed-loop Detection System for Multi-target Spectral Telescope. The LAMOST telescope has been operating steadily for more than 10 yr and is currently undergoing an upgrade to its fiber-optic positioning system on the telescope's focal plane. By adding a vision detection system to accurately measure the current position of the optical fibres and carry out closed-loop feedback control, the positioning accuracy of the original optical fiber system is greatly improved. Due to the limitation of the existing optical path of the telescope, to avoid blocking the optical path, the detection system camera cannot be placed on the optical axis of the telescope, which makes the camera and the optical fiber end face at a relatively inclined position. However, the angle between the camera and an object will introduce errors to the polynomial calibration method used in the visual detection system. To address this problem, by analyzing the relationship between the camera imaging principle and the polynomial calibration method, this paper studies the influence of distortion and imaging angle on polynomial calibration results under different angle conditions and proposes an improved high-precision polynomial calibration method. First, the distortion parameters are calculated using Zhang's method, and the image distortion is removed. Then, a mapping model between oblique plane image and nonoblique plane image is established through a homography matrix. The coordinates of all oblique plane feature points are mapped one by one to the nonoblique plane positions on the image space, and a good correction effect is obtained. Finally, the calibration images from different angles are calculated and analyzed through simulation experiments and compared with Zhang's method. The results show that this method has a 10%-40% improvement over Zhang's method.

Keywords: Photogrammetry, Astronomical techniques, Astronomical instrumentation
Characterization of a pnCCD-based Camera for Applications at the 100 m X-Ray Test Facility. The 100 m long X-ray test facility (100XF for clarity) in Institute of High Energy Physics of CAS has been playing an increasingly important role in the X-ray astronomy field in China. 100XF has been contributing to the missions under development, such as the Einstein Probe mission. The facility has also been providing support to R&amp;D of focusing X-ray optics in China that will enable future X-ray telescopes to be realized, such as the enhanced X-ray Timing and Polarization (eXTP) mission. A pnCCD-based camera has been employed at 100XF to rapidly measure the performance of the X-ray optics. In this work, we study the performance of the camera and its spectral and imaging applications at 100XF. The camera system can provide a high frame readout rate, with a low readout noise &lt;3 e-. It is sensitive to X-ray photons in the 3-10 keV energy band with a high quantum efficiency exceeding 90%. Actually, the low threshold of detection energy range can reach down to 0.2 keV. The energy resolution can reach 145.2 eV for single events and 154.8 eV for all valid events (including single events and split events) at 6.4 keV. The camera also exhibits excellent imaging capability in both the full frame mode and the windowing mode, with a readout rate of up to 1000 Hz. Finally, a prototype of a focusing X-ray mirror shell of eXTP was smoothly measured with this camera. The obtained on-axis point-spread function and half-power diameter are consistent with expectations. It is proven that the camera can improve the capability of 100XF in characterizing the X-ray optics. This camera will be very useful for performing on-ground calibrations for future X-ray telescope missions. *Released on xxx, XXst, 2023.

Keywords: Calibration, X-ray detectors, Astronomical instrumentation
The Large Array Survey Telescope-System Overview and Performances. The Large Array Survey Telescope (LAST) is a wide-field visible-light telescope array designed to explore the variable and transient sky with a high cadence. LAST will be composed of 48, 28 cm f/2.2 telescopes (32 already installed) equipped with full-frame backside-illuminated cooled CMOS detectors. Each telescope provides a field of view (FoV) of 7.4 deg2 with 1.″25 pix-1, while the system FoV is 355 deg2 in 2.9 Gpix. The total collecting area of LAST, with 48 telescopes, is equivalent to a 1.9 m telescope. The cost-effectiveness of the system (i.e., probed volume of space per unit time per unit cost) is about an order of magnitude higher than most existing and under-construction sky surveys. The telescopes are mounted on 12 separate mounts, each carrying four telescopes. This provides significant flexibility in operating the system. The first LAST system is under construction in the Israeli Negev Desert, with 32 telescopes already deployed. We present the system overview and performances based on the system commissioning data. The B p 5σ limiting magnitude of a single 28 cm telescope is about 19.6 (21.0), in 20 s (20 × 20 s). Astrometric two-axes precision (rms) at the bright-end is about 60 (30) mas in 20 s (20 × 20 s), while absolute photometric calibration, relative to GAIA, provides ~10 millimag accuracy. Relative photometric precision, in a single 20 s (320 s) image, at the bright-end measured over a timescale of about 60 minutes is about 3 (1) millimag. We discuss the system science goals, data pipelines, and the observatory control system in companion publications.

Keywords: Surveys, Telescopes
The James Webb Space Telescope Mission. Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least 4 m. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the 6.5 m James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 yr, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.

Keywords: Space vehicle instruments, Infrared astronomy, Space observatories, History of astronomy, Astronomical instrumentation, Infrared observatories
A Study of Twelve Potential Merger Candidate Contact Binary Systems. Photometric observations and analysis of twelve previously poorly studied contact binary systems is presented. All show total eclipses and have extremely low mass ratios ranging from 0.072 to 0.15. Also, all show characteristics of orbital instability with mass ratios within the theoretical orbital instability range. Although none demonstrate a significant O'Connell effect at least nine of the systems have other indicators of increased chromospheric and magnetic activity.

Keywords: Orbital elements, Transient detection, Contact binary stars
Micro-arcsecond Astrometry Technology: Detector and Field Distortion Calibration. Microarcsecond (μas) astrometry is an indispensable technique to detect earth-like exoplanets, fully characterize exoplanetary orbits, and measure their masses-information critical for assessing their habitability. Highly accurate astrometric measurements can also probe the nature of dark matter, the early universe, black holes, and neutron stars, thus providing unique data for new astrophysics. This paper presents technologies of calibrating detectors and field distortions for achieving narrow field μas relative astrometry with a focal plane array detector on a 6 m telescope.

Keywords: Calibration, Astrometry
Investigating the Multiband Nonthermal Radiative Properties of HESS J1420-607. HESS J1420-607 is a γ-ray emitting source associated with the pulsar wind nebula (PWN) powered by the energetic pulsar PSR J1420-6048. Based on 14 yr of data obtained with the Fermi Large Area Telescope, we re-analyzed its GeV γ-ray radiative properties, resulting in detailed spectra obtained within the band 10-200 GeV. Moreover, we use a one-zone time-dependent model for the multiband nonthermal emission from pulsar wind nebulae to investigate the radiative properties of the nebula associated with HESS J1420-607. Assuming that the electrons/positrons are injected into the PWN with a broken power law spectrum with indexes of ~1.6 and ~2.7, as well as a break Lorentz factor of ~5 × 106, the results indicate that the multi-wavelength spectral energy distribution is consistent with the detected fluxes in both X-rays and γ-rays. The results support that the γ-rays detected can be produced via inverse Compton scattering of the energetic electrons/positrons within the PWN.

Keywords: Supernova remnants, Gamma-ray sources, Nebulae, Pulsar wind nebulae
The MPI + CUDA Gaia AVU-GSR Parallel Solver Toward Next-generation Exascale Infrastructures. We ported to the GPU with CUDA the Astrometric Verification Unit-Global Sphere Reconstruction (AVU-GSR) Parallel Solver developed for the ESA Gaia mission, by optimizing a previous OpenACC porting of this application. The code aims to find, with a [10, 100] μarcsec precision, the astrometric parameters of ~108 stars, the attitude and instrumental settings of the Gaia satellite, and the global parameter γ of the parametrized Post-Newtonian formalism, by solving a system of linear equations, A × x = b , with the LSQR iterative algorithm. The coefficient matrix A of the final Gaia data set is large, with ~1011 × 108 elements, and sparse, reaching a size of ~10-100 TB, typical for the Big Data analysis, which requires an efficient parallelization to obtain scientific results in reasonable timescales. The speedup of the CUDA code over the original AVU-GSR solver, parallelized on the CPU with MPI + OpenMP, increases with the system size and the number of resources, reaching a maximum of ~14×, &gt;9× over the OpenACC application. This result is obtained by comparing the two codes on the CINECA cluster Marconi100, with 4 V100 GPUs per node. After verifying the agreement between the solutions of a set of systems with different sizes computed with the CUDA and the OpenMP codes and that the solutions showed the required precision, the CUDA code was put in production on Marconi100, essential for an optimal AVU-GSR pipeline and the successive Gaia Data Releases. This analysis represents a first step to understand the (pre-)Exascale behavior of a class of applications that follow the same structure of this code. In the next months, we plan to run this code on the pre-Exascale platform Leonardo of CINECA, with 4 next-generation A200 GPUs per node, toward a porting on this infrastructure, where we expect to obtain even higher performances.

Keywords: Computational methods, Galaxy kinematics, Astrometry, Astronomy software
The Near Infrared Imager and Slitless Spectrograph for the James Webb Space Telescope. III. Single Object Slitless Spectroscopy. The Near Infrared Imager and Slitless Spectrograph instrument (NIRISS) is the Canadian Space Agency contribution to the suite of four science instruments of the James Webb Space Telescope. As one of the three NIRISS observing modes, the Single Object Slitless Spectroscopy (SOSS) mode is tailor-made to undertake time-series observations of exoplanets to perform transit spectroscopy. The SOSS permits observing point sources between 0.6 and 2.8 μm at a resolving power of 650 at 1.25 μm using a slitless cross-dispersing grism while its defocussing cylindrical lens enables observing targets as bright as J = 6.7 by spreading light across 23 pixels along the cross-dispersion axis. This paper officially presents the design of the SOSS mode, its operation, characterization, and its performance, from ground-based testing and flight-based commissioning. On-sky measurements demonstrate a peak photon conversion efficiency of 55% at 1.2 μm. The first time series on the A-type star BD+60°1753 achieves a flux stability close to the photon-noise limit, so far tested to a level of 20 parts per million on a 40 minute timescale after simply subtracting a long-term trend. Uncorrected 1/f noise residuals underneath the spectral traces add an extra source of noise equivalent to doubling the readout noise. Preliminary analysis of an HAT-P-14b transit time series indicates that it is difficult to remove all of the noise in pixels with partially saturated ramps. Overall, the SOSS delivers performance at the level required to tackle key exoplanetary science programs such as detecting secondary atmospheres on terrestrial planets and measuring abundances of several chemical species in gas giants.

Keywords: Infrared astronomy, Astronomical instrumentation, Exoplanet atmospheres
QTT Ultra-wideband Signal Acquisition and Baseband Data Recording System Design Based on the RFSoC Platform. The 110 m QiTai radio Telescope (QTT) will be equipped with multiple Ultra-WideBand (UWB) receivers in the primary and Gregory focus to achieve continuous frequency coverage from 270 MHz to 115 GHz, which poses great challenges to signal acquisition, transmission, and real-time processing. Aiming at 10 GHz and above full-bandwidth acquisition and multi-scientific processing for the QTT UWB signals, an experimental system with high-speed signal acquisition, 100 Gb network multi-path distribution, and fast recording is designed by using advanced direct RF-sampling technology and heterogeneous architecture. The system employs a ZCU111 board to digitize dual-polarization signals with a sampling rate of 4.096 GigaSamples-Per-Second and 12-bit quantization. The collected wideband signals are channelized into 2048 chunks, which are then assembled into 16 sets of digital narrow basebands with 128 MHz bandwidth and transmitted to the processing servers through two 100 Gb ports. A HASPIPE pipeline, UWB_HASHPIPE is designed to receive and store multiple subbands in parallel. Data distribution links can be flexibly configured based on IP addresses and port numbers. The system is verified by pulsar observation experiments on the Nanshan 26 m telescope. 512 MHz bandwidth is selected from the collected L-band receiver signals and recorded in VDIF file format with 8 parallel instances. The test results show that the data integrity is excellent, and the signal-to-noise ratio of the band-merged pulsar profile is stronger than single subband data. This paper provides a high-performance and flexible solution for the design of versatile UWB backends. Meanwhile, the developed platform can be integrated into QTT backends for baseband data collection and Very Long Baseline Interferometry observation.

Keywords: Radio spectroscopy, Astronomy data acquisition, Astronomical techniques, Radio telescopes, Astronomical instrumentation
JWST MIRI Flight Performance: Detector Effects and Data Reduction Algorithms. The detectors in the Mid-Infrared Instrument (MIRI) of the James Webb Space Telescope (JWST) are arsenic-doped silicon impurity band conduction (Si:As IBC) devices and are direct descendants of the Spitzer IRAC long wavelength arrays (channels 3 and 4). With appropriate data processing, they can provide excellent performance. In this paper we discuss the various non-ideal behaviors of these detectors that need to be addressed to realize their potential. We have developed a set of algorithms toward this goal, building on experience with previous similar detector arrays. The MIRI-specific stage 1 pipeline algorithms, of a three stage JWST calibration pipeline, were developed using pre-flight tests on the flight detectors and flight spares and have been refined using flight data. This paper describes these algorithms, which are included in the first stage of the JWST Calibration Pipeline for the MIRI instrument.

Keywords: Astronomy software, Astronomy data reduction
Similar Image Retrieval using Autoencoder. I. Automatic Morphology Classification of Galaxies. We present the construction of an image similarity retrieval engine for the morphological classification of galaxies using the Convolutional AutoEncoder (CAE). The CAE is trained on 90,370 preprocessed Sloan Digital Sky Survey galaxy images listed in the Galaxy Zoo 2 (GZ2) catalog. The visually similar output images returned by the trained CAE suggest that the encoder efficiently compresses input images into latent features, which are then used to calculate similarity parameters. Our Tool for Searching a similar Galaxy Image based on a Convolutional Autoencoder using Similarity (TSGICAS) leverages this similarity parameter to classify galaxies' morphological types, enabling the identification of a wider range of classes with high accuracy compared to traditional supervised ML techniques. This approach streamlines the researcher's work by allowing quick prioritization of the most relevant images from the latent feature database. We investigate the accuracy of our automatic morphological classifications using three galaxy catalogs: GZ2, Extraction de Formes Idéalisées de Galaxies en Imagerie (EFIGI), and Nair &amp; Abraham (NA10). The correlation coefficients between the morphological types of input and retrieved galaxy images were found to be 0.735, 0.811, and 0.815 for GZ2, EFIGI, and NA10 catalogs, respectively. Despite differences in morphology tags between input and retrieved galaxy images, visual inspection showed that the two galaxies were very similar, highlighting TSGICAS's superior performance in image similarity search. We propose that morphological classifications of galaxies using TSGICAS are fast and efficient, making it a valuable tool for detailed galaxy morphological classifications in other imaging surveys.

Keywords: Hubble classification scheme, Galaxy classification systems
Color Transformations of Photometric Measurements of Galaxies in Optical and Near-infrared Wide-field Imaging Surveys. Over the past 2 decades, wide-field photometric surveys in optical and infrared domains reached a nearly all-sky coverage thanks to numerous observational facilities operating in both hemispheres. However, subtle differences among exact realizations of Johnson and SDSS photometric systems require one to convert photometric measurements into the same system prior to analysis of composite data sets originating from multiple surveys. It turns out that the published photometric transformations lead to substantial biases when applied to integrated photometry of galaxies from the corresponding catalogs. Here we present photometric transformations based on piece-wise linear approximations of integrated photometry of galaxies in the optical surveys SDSS, DECaLS, BASS, MzLS, DES, DELVE, KiDS, VST ATLAS, and the near-infrared surveys UKIDSS, UHS, VHS, and VIKING. We validate our transformations by constructing k-corrected color-magnitude diagrams of non-active galaxies and measuring the position and tightness of the "red sequence." We also provide transformations for aperture magnitudes and show how they are affected by the image quality difference among the surveys. We present the implementation of the derived transformations in PYTHON and IDL and also a web-based color transformation calculator for galaxies. By comparing DECaLS and DES, we identified systematic issues in DECaLS photometry for extended galaxies, which we attribute to the photometric software package used by DECaLS. As an application of our method, we compiled two multi-wavelength photometric catalogs for over 200,000 low- and intermediate-redshift galaxies originating from CfA FAST and Hectospec spectral archives. *An online color transformation calculator is available at: https://colors.voxastro.org/.

Keywords: Galaxy colors, Photometric systems, Galaxy photometry, Color equation
Comparison Between TeV and Non-TeV Fermi-detected BL Lacertae Objects. In this paper, we compiled a sample of 410 Fermi-detected BL Lacs, including 42 TeV-detected BL Lacs (TBLs) and 368 non-TeV-detected BL Lacs (non-TBLs) with corresponding mid-infrared (mid-IR), TeV and Fermi γ-ray data, and calculated some important parameters including monochromatic luminosities (mid-IR, GeV and TeV bands) and mid-IR spectral indices. Based on those parameters, we discussed the relationship between the mid-IR and the TeV bands and that between the mid-IR and the GeV bands. Main conclusions are drawn as follows: (1) In the color-color and color-magnitude diagrams, our sample forms a WISE-Gamma Strip in the [3.4]-[4.6]-[12] μm color-color diagram, and TBLs occupy the brighter region than the non-TBLs for the similar color-index in the color-magnititue diagram; (2) The mid-IR luminosity of the TBLs is on average higher than that of non-TBLs, while the average mid-IR spectral index of TBLs is smaller than the non-TBLs, suggesting that TBLs are brighter and hold a more flat spectrum than do the non-TBLs in the mid-IR band. Besides, HBLs have a more flat mid-IR spectrum than LBLs and IBLs; (3) The mid-IR luminosity is positively correlated with the GeV luminosity and the intrinsic TeV luminosity. A positive correlation exists between the mid-IR spectral index and the observed TeV spectral index, which is consistent with the expectations of the synchrotron self-Compton mechanism. We suggest that the HBLs with extreme relativistic electrons might scatter the mid-IR photons up to the TeV band.

Keywords: Blazars, Active galactic nuclei, Gamma-rays, BL Lacertae objects