Sazuna/UAT_keywords huggingface dataset:
Be X-Ray Binaries as Progenitors of Double Neutron Stars: Evidence of Similar bi-modal Classifications. We explore the evolutional links between Be X-ray binaries (BeXBs) and double neutron stars (DNSs) by analyzing their physical parameters and classifications. We find that both BeXBs and DNSs show positive correlation trends between the neutron star (NS) spin period─P and binary orbital period─P orb, which may relate to the influence of binary accretion. In addition, BeXBs show a bi-modal classification divided by P ∼ 40 s/P orb ∼ 60 days, where BeXBs with P &lt; 40 s/P orb &lt; 60 days exhibit stronger accretion-induced properties, e.g., the lower average NS magnetic field strength, than those with P &gt; 40 s/P orb &gt; 60 days. Similarly, DNSs exhibit a bi-modal classification divided by P orb ∼ 1 day, where DNSs with P orb &lt; 1 day share the stronger accretion-induced properties, e.g., the higher average accretion rate of the recycled NSs, than those with P orb &gt; 1 day. The multi-parameter analysis with the new aggregated data set improves the knowledge of the bi-modal classifications of BeXBs/DNSs. In addition, we consider the influence of the common envelope phase/supernova kick of the donor star on the evolution from BeXBs to DNSs, and further discuss their compatibility with the observed bi-modal classifications of BeXBs/DNSs. Last, we propose a potential evolutional relation between the bi-modal BeXBs and DNSs.

Keywords: Neutron stars, X-ray binary stars, Binary pulsars, Pulsars
How Accurate are Transient Spectral Classification Tools?— A Study Using 4646 SEDMachine Spectra. Accurate classification of transients obtained from spectroscopic data are important to understand their nature and discover new classes of astronomical objects. For supernovae (SNe), SNID, NGSF (a Python version of SUPERFIT), and DASH are widely used in the community. Each tool provides its own metric to help determine classification, such as rlap of SNID, chi2/dof of NGSF, and Probability of DASH. However, we do not know how accurate these tools are, and they have not been tested with a large homogeneous data set. Thus, in this work, we study the accuracy of these spectral classification tools using 4646 SEDMachine spectra, which have accurate classifications obtained from the Zwicky Transient Facility Bright Transient Survey (BTS). Comparing our classifications with those from BTS, we have tested the classification accuracy in various ways. We find that NGSF has the best performance (overall Accuracy 87.6% when samples are split into SNe Ia and Non-Ia types), while SNID and DASH have similar performance with overall Accuracy of 79.3% and 76.2%, respectively. Specifically for SNe Ia, SNID can accurately classify them when rlap &gt; 15 without contamination from other types, such as Ibc, II, SLSN, and other objects that are not SNe (Purity &gt; 98%). For other types, determining their classification is often uncertain. We conclude that it is difficult to obtain an accurate classification from these tools alone. This results in additional human visual inspection effort being required in order to confirm the classification. To reduce this human visual inspection and to support the classification process for future large-scale surveys, this work provides supporting information, such as the accuracy of each tool as a function of its metric.

Keywords: Classification, Surveys, Astronomy data analysis, Spectroscopy, Supernovae
High-pass Filter Periodogram: An Improved Power Spectral Density Estimator for Unevenly Sampled Data. Accurate time series analysis is essential for studying variable astronomical sources, where detecting periodicities and characterizing power spectral density (PSD) are crucial. The Lomb–Scargle periodogram, commonly used in astronomy for analyzing unevenly sampled time series data, often suffers from noise introduced by irregular sampling. This paper presents a new high-pass filter (HPF) periodogram, a novel implementation designed to mitigate this sampling-induced noise. By applying a frequency-dependent HPF before computing the periodogram, the HPF method enhances the precision of PSD estimates and periodicity detection across a wide range of signal characteristics. Simulations and comparisons with the Lomb–Scargle periodogram demonstrate that the HPF periodogram improves accuracy and reliability under challenging sampling conditions, making it a valuable complementary tool for more robust time series analysis in astronomy and other fields dealing with unevenly sampled data.

Keywords: Lomb-Scargle periodogram, Astronomy data analysis, Period search , Time domain astronomy, Time series analysis
Theoretical Performance Evaluation of Wide-band Diffraction-limited Coronagraph for the Next-generation Segmented Large Telescopes. We investigate the raw-contrast mitigation ability of the spectroscopic coronagraph. We consider a mis-modulation of the complex amplitude by the transmissive focal-plane mask that is an intrinsic problem dependent on the spectral resolving power of a grating in a spectroscopic coronagraph, stellar angular radius, and non-common path error (NCP) that is due to chromaticity in the active wavefront control (WFC) as limitation factors to the performance of the spectroscopic coronagraph. Concerning the impact of the mis-modulation and stellar angular radius under the assumption with the an achromatic WFC, we found that the spectroscopic coronagraph potentially archives the raw-contrast of 1.25 × 10‑10 at the spectral resolving power R greater than or equal to 2000 at   with the 10 pc distant solar radius 0.93 mas. It corresponds to approximately 0.03λ/D where the wavelength λ is 800 nm and telescope diameter D is 6 m. The inner working angle (defined as the minimal angular distance where planetary throughput is the maximal throughput) of the spectroscopic coronagraph is  . In addition, we found that the NCP limits the raw-contrast mitigation ability to 7.3 × 10‑11 and 5.5 × 10‑10 at   for 3% and 8% spectral bandwidths, respectively. We conclude that the spectroscopic coronagraph may serve as a promising method of broadband direct imaging of potentially habitable exoplanets located at small inner working angles with the next-generation segmented large telescopes.

Keywords: Astronomical optics, Coronagraphic imaging, Direct imaging, Astronomical instrumentation, Exoplanet detection methods
Visible-light High-contrast Imaging and Polarimetry with SCExAO/VAMPIRES. We present significant upgrades to the Visible Aperture-Masking Polarimetric Imager/Interferometer for Resolving Exoplanetary Signatures (VAMPIRES) instrument, a visible-light (600–800 nm) high-contrast imaging polarimeter integrated within SCExAO on the Subaru telescope. Key enhancements include new qCMOS detectors, coronagraphs, polarization optics, and a multiband imaging mode, improving sensitivity, resolution, and efficiency. These upgrades position VAMPIRES as a powerful tool for studying sub-stellar companions, accreting protoplanets, circumstellar disks, stellar jets, stellar mass-loss shells, and solar system objects. The instrument achieves angular resolutions from 17 to 21 mas and Strehl ratios up to 60%, with 5σ contrast limits of 10‑4 at 0.″1 to 10‑6 beyond 0.″5. We demonstrate these capabilities through spectro-polarimetric coronagraphic imaging of the HD 169142 circumstellar disk, ADI+SDI imaging of the sub-stellar companion HD 1160B, narrowband Hα imaging of the R Aqr emission nebula, and spectro-polarimetric imaging of Neptune.

Keywords: Spectropolarimetry, Optical astronomy, Astronomical optics, Coronagraphic imaging, Astronomical detectors, Direct imaging, Astronomical instrumentation, Polarimetry, Interferometry
KISS: Instrument Description and Performance. Kinetic inductance detectors (KIDs) have been proven as reliable systems for astrophysical observations, especially in the millimeter range. Their compact size enables them to optimally fill the focal plane, thus boosting sensitivity. The KIDs Interferometric Spectral Surveyor (KISS) instrument is a millimeter camera that consists of two KID arrays of 316 pixels each coupled to a Martin─Puplett interferometer (MPI). The addition of the MPI grants the KID camera the ability to provide spectral information in the 100 and 300 GHz range. In this paper, we report the main properties of the KISS instrument and its observations. We also describe the calibration and data analysis procedures used. We present a complete model of the observed data including the sky signal and several identified systematics. We have developed a full photometric and spectroscopic data analysis pipeline that translates our observations into science-ready products. We show examples of the results of this pipeline on selected sources: the Moon, Jupiter, and Venus. We note the presence of a deficit of response with respect to expectations and laboratory measurements. The detector's noise level is consistent with values obtained during laboratory measurements, pointing to a suboptimal coupling between the instrument and the telescope as the most probable origin for the problem. This deficit is large enough to prevent the detection of galaxy clusters, which were KISS's main scientific objective. Nevertheless, we have demonstrated the feasibility of this kind of instrument in the prospect of other KID interferometers (such as the CONCERTO instrument). In this regard, we have developed key instrumental technologies such as optical conception, readout electronics, and raw calibration procedures, as well as adapted data analysis procedures.

Keywords: Millimeter astronomy, Astronomical techniques, Astronomy data acquisition
Lossy Compression of Integer Astronomical Images Preserving Photometric Properties. Observatories are producing astronomical image data at quickly increasing rates. As a result, the efficiency of the compression methods employed is critical to meet the storage and distribution requirements of both observatories and scientists. This paper presents a novel lossy compression technique that is able to preserve the results of photometry analysis with high fidelity while improving upon the state of the art in terms of compression performance. The proposed compression pipeline combines a flexible bi-region quantization scheme with the lossless, dictionary-based, LPAQ9M encoder. The quantization process allows compression performance and photometric fidelity to be precisely tailored to different scientific requirements. A representative data set of 16-bit integer astronomical images produced by telescopes from all around the world has been employed to empirically assess its compression-fidelity trade-offs, and compare them to those of the de facto standard Fpack compressor. In these experiments, the widespread SExtractor software is employed as the ground truth for photometric analysis. Results indicate that after lossy compression with our proposed method, the decompressed data allows consistent detection of over 99% of all astronomical objects for all tested telescopes, maintaining the highest photometric fidelity (as compared to state of the art lossy techniques). When compared to the best configuration of Fpack (Hcompress lossy using 1 quantization parameter) at similar compression rates, our proposed method provides better photometry precision: 7.15% more objects are detected with magnitude errors below 0.01, and 9.13% more objects with magnitudes below SExtractor's estimated measurement error. Compared to the best lossless compression results, the proposed pipeline allows us to reduce the compressed data set volume by up to 38.75% and 27.94% while maintaining 90% and 95%, respectively, of the detected objects with magnitude differences lower than 0.01 mag; and up to 18.93% while maintaining 90% of the detected objects with magnitude differences lower than the photometric measure error. *This work was supported in part by the Spanish Ministry of Science and Innovation (MICINN) and by the European Regional Development Fund (FEDER), funded by MCIN/AEI/10.13039/501100011033/FEDER, UE, under grant PID2021-125258OB-I00; also by the Catalan Government under grant SGR2021-00643; and also by the "PhotSat" project under the Institute for Space Studies of Catalonia (IEEC) and the Catalan Government.

Keywords: Astronomy software, Astronomy data analysis, Astronomy data reduction
Multi-station Meteor Monitoring (M<SUP>3</SUP>) System. II. System Upgrade and a Pathfinder Network. Meteors are important phenomena reflecting many properties of interplanetary dust particles. The study of their origin, mass distribution, and orbit evolution requires a large data volume, which can only be obtained using large meteor networks. After meteor networks in Europe and America, we present our designs and upgrades of a proposed network in China. The new designs are mainly aimed at facilitating the data gathering process. Each of the newly designed meteor stations can now support up to four cameras to cover the full sky. A newer version of the meteor station software now works as an integral system, which can streamline the process of detecting, measuring, and uploading meteors. We have built a meteor data platform to store, process, and display the meteor data automatically. The software and data platform are designed to be easy to learn and use, so they can attract more people to join and operate meteor stations. Four stations are installed as the first phase of the network, and during the operation, in 10 months, the network detected 8683 orbits; we find that half of the orbits can be related to established meteoroid streams. The statistical analysis of sporadic meteoroids shows a bimodal distribution of the velocities, which coincides with previous studies. The distribution of Tisserand parameters, T  j , shows the two peaks at T  j  = 0 and 3, indicating the different orbits of parent bodies (isotropic and ecliptic), which are divided by T  j  = 2. The falling trajectory of a meteorite was also predicted using the observational data of the network. We are currently expanding the network, and in the future, we will carry out a detailed analysis of the key parameters of the distribution of the meteoroids.

Keywords: Meteoroids, Meteor streams, Meteors, Meteorites, All-sky cameras
Constraints on Testing Post-Newtonian Gravity with Scanning Space Astrometry. High-precision astrometry has the capability of testing General Relativity in the framework of the parametrized post-Newtonian formalism (PPN). Accurate measurements of gravitational light deflection over the entire celestial sphere open up a potential opportunity for determining the post-Newtonian parameter γ, which governs the deflection strength. We examine both analytically and numerically the coupling between a global parallax shift and the PPN parameter γ in Gaia-like astrometry. We also study effect of a parallax zero point on PPN γ estimation is scanning space astrometry. Least squares technique is applied to a direct astrometric solution including PPN γ and astrometric parameters (positions, parallax and proper motions). Analytical solution of the normal equations provides covariance information for the parameter γ and parallaxes. We present a new treatment of the correlation between parallax zero point and PPN γ, based on a statistical approach. We also derive a formula describing the bias in PPN γ estimation resulting from a global parallax offset. These theoretical results are verified by Monte Carlo experiments using astrometric solutions with simulated Gaia observations. Parallax zero point at a sub-μas level is needed to obtain a PPN γ estimate comparable with today's best determination. We generalize the problem to two-dimensional observations and derive formula for the correlation between parallax zero point and PPN γ in the case when both along- and across-scan measurements are used for PPN γ determination.

Keywords: Trigonometric parallax, Gravitation, Astronomy data analysis, Astrostatistics, Space astrometry, Astrometry
Mercury's Meteorite Mysteries: A Directional Statistical Guide to Mercury's North Pole, Hidden Hazards and Roadmap to Safe Landing Havens Based on Solar Elevation, Ice Stability, Temperature. Studying meteoroid impact patterns on planetary surfaces is critical for understanding surface dynamics and selecting safe landing sites. Mercury, one of the least explored rocky planets, presents unique challenges due to its extreme temperatures and the angular nature of its surface data. Traditional linear statistical methods are often inadequate for analyzing such directional data. This study introduces a novel approach using directional data analysis techniques to interpret the cyclical nature of meteoroid impact locations on Mercury. We employed Watson's test, Bayesian Information Criterion scores, and a mixture of von Mises–Fisher distributions to model the distribution of impact craters and solar elevations on Mercury's surface. Our findings indicate that while location parameters adhere to the von Mises distribution, solar elevations do not exhibit directional distribution characteristics. Additionally, by filtering datasets based on temperature thresholds and crater diameters, we pinpointed areas with a high probability of providing suitable landing surfaces. These insights enhance our understanding of the surface conditions on Mercury and provide valuable groundwork for future exploration missions.

Keywords: Meteorites, Meteor showers, Planetary science, Solar system astronomy
Absolute Reference for Microwave Polarization Experiments. The COSMOCal Project and its Proof of Concept. Context. The cosmic microwave background (CMB), a remnant of the Big Bang, provides unparalleled insights into the primordial universe, its energy content, and the origin of cosmic structures. The success of forthcoming terrestrial and space experiments hinges on meticulously calibrated data. Specifically, the ability to achieve an absolute calibration of the polarization angles with a precision of &lt;0.°1 is crucial to identify the signatures of primordial gravitational waves and cosmic birefringence within the CMB polarization. Aims. We introduce the COSmological Microwave Observations Calibrator project, designed to deploy a polarized source in space for calibrating microwave frequency observations. The project aims to integrate microwave polarization observations from small and large telescopes, ground-based and in space, into a unified scale, enhancing the effectiveness of each observatory and allowing robust combination of data. Methods. To demonstrate the feasibility and confirm the observational approach of our project, we developed a prototype instrument that operates in the atmospheric window centered at 260 GHz, specifically tailored for use with the NIKA2 camera at the IRAM 30 m telescope. Results. We present the instrument components and their laboratory characterization. The results of tests performed with the fully assembled prototype using a Kinetic Inductance Detectors-based instrument, similar concept of NIKA2, are also reported. Conclusions. This study paves the way for an observing campaign using the IRAM 30 m telescope and contributes to the development of a space-based instrument.

Keywords: Cosmic microwave background radiation, Observational cosmology, Calibration, Astronomical instrumentation, Polarimetry
System Design for a Wide Field-of-view Near-infrared Telescope for Dome A in Antarctica. Dome A in Antarctica likely has the best observing conditions on the Earth's surface in the near-infrared owing to its sky-light background and superior seeing conditions. This work introduces the system design and on-sky performance of the first wide field-of-view near-infrared telescope at Dome A. We present the lens design, tolerance analysis and stray light analysis of the optical system. We then evaluate a preliminary alignment method suitable for daytime use based on visual inspection. Finally, we describe a direct drive motor with maze structures, and an optical system with thermal compensation that is specially designed for the extreme environment in Antarctica. The on-sky performances demonstrate that this pilot near-infrared telescope not only successfully explores new technologies for extreme environments, but also presents an opportunity for 2670 hr of uninterrupted synergistic observation with the 0.5 m AST3-2 telescope at Dome A. The distinctive attributes of our design render it invaluable in many astronomical fields and holds significant promise for the monitoring of space debris and near-earth asteroids.

Keywords: Antarctic observatories, Sky brightness, Telescopes, Near infrared astronomy
The BlackGEM Telescope Array. I. Overview. The main science aim of the BlackGEM array is to detect optical counterparts to gravitational wave mergers. Additionally, the array will perform a set of synoptic surveys to detect Local Universe transients and short timescale variability in stars and binaries, as well as a six-filter all-sky survey down to ∼22nd mag. The BlackGEM Phase-I array consists of three optical wide-field unit telescopes. Each unit uses an f/5.5 modified Dall-Kirkham (Harmer-Wynne) design with a triplet corrector lens, and a 65 cm primary mirror, coupled with a 110Mpix CCD detector, that provides an instantaneous field-of-view of 2.7 square degrees, sampled at 0.″564 pixel‑1. The total field-of-view for the array is 8.2 square degrees. Each telescope is equipped with a six-slot filter wheel containing an optimised Sloan set (BG-u, BG-g, BG-r, BG-i, BG-z) and a wider-band 440–720 nm (BG-q) filter. Each unit telescope is independent from the others. Cloud-based data processing is done in real time, and includes a transient-detection routine as well as a full-source optimal-photometry module. BlackGEM has been installed at the ESO La Silla observatory as of 2019 October. After a prolonged COVID-19 hiatus, science operations started on 2023 April 1 and will run for five years. Aside from its core scientific program, BlackGEM will give rise to a multitude of additional science cases in multi-colour time-domain astronomy, to the benefit of a variety of topics in astrophysics, such as infant supernovae, luminous red novae, asteroseismology of post-main-sequence objects, (ultracompact) binary stars, and the relation between gravitational wave counterparts and other classes of transients.

Keywords: Gravitational wave astronomy, Optical telescopes, Sky surveys, Transient detection
Discerning the Very-high-energy Component via the Variation of γ-Rays in PKS 1510‑089. The discovery and identification of very-high-energy (VHE) γ-ray emission of blazars is important for understanding active galactic nucleus jets. Based on Fermi-LAT observations, we find that PKS 1510‑089 exhibits a softer-when-brighter trend at the low γ-ray flux level and changes to the harder-when-brighter trend at the high γ-ray flux level. Such a trend transition could be naturally explained by the presence of the VHE component, recently confirmed by the H.E.S.S. Collaboration. To reproduce the trend transition, we construct a two-component model that includes the high-energy (HE) component and the VHE component and consider two variation mechanisms including the change of the Doppler factor and the intrinsic peak frequency. The result is that such a trend transition in the Fermi-LAT range can be better explained by the shift of the peak frequency of the HE component. Combining the broadband spectral energy distribution analysis, we suggest that the HE component may originate from the jet at the broad-line region scale, and the VHE component may originate from the jet at the dust torus scale. The advantage of the spectral variation method enables us to discover the rich VHE emission across blazars.

Keywords: Blazars