Sazuna/UAT_keywords huggingface dataset:
An X-Ray Optic System Ray-tracing Package for FXT on Board EP Satellite. The Einstein Probe (EP) mission, launched in 2024 January, is a time-domain X-ray satellite designed to discover and study X-ray transient and burst sources while investigating electromagnetic counterparts to gravitational waves. To achieve precise observations, EP features the Follow-up X-ray Telescope (FXT), equipped with two Wolter-I type mirrors for precise imaging within a 1 square degree field of view. A specialized Ray-Tracing package for the FXT (RTF) was developed to assess the Wolter-I type mirrors' performance used in FXT. By employing specialized algorithms to simulate X-ray photon total reflection, RTF has yielded valuable insights into key optical parameters such as point-spread function, effective area, and vignetting. The package also evaluates components like the X-ray baffle and filter wheel, further enhancing the optical system's efficacy. Moreover, the ray-tracing results have been validated against measurements. These simulations are crucial for ground calibration and will assist in maximizing the scientific output of the EP mission by improving the understanding of mirrors' behavior in various observational conditions.

Keywords: Astronomical instrumentation, Astronomy software, X-ray telescopes
An Experiment to Observe GNSS Signals with the Australian VGOS Array. This paper introduces a new instrument enabling a novel combination of Earth measuring techniques: direct observations with the radio astronomical instruments to satellites of the global navigation satellite systems (GNSS). Inter-technique biases are a major error source in the terrestrial reference frame. Combining two major space-geodetic techniques, GNSS and Very Long Baseline Interferometry (VLBI), through observations to identical sensors has been considered infeasible due to their seemingly incompatible operating frequencies. The newly accessible L-band capability of the Australian VLBI Global Observing System telescopes is shown here, invalidating this prevailing opinion. A series of test observations demonstrate geodetic VLBI observations to Global Positioning System satellites for a continental-wide IVS telescope array, with the potential for observations at a critical scale. We anticipate immediate impact for the geodetic community, through first-ever inter-technique ties between VLBI and GNSS in the Australian region and via the opportunity for critical test observations toward the Genesis mission, geodesy's flagship project in the area of space ties set for launch in 2028.

Keywords: Very long baseline interferometry, Astronomical instrumentation
Optimizing Charge-coupled Device Readout Enabled by the Floating-gate Amplifier. Multiple-Amplifier Sensing (MAS) charge-coupled devices (CCDs) have recently been shown to be promising silicon detectors that meet noise sensitivity requirements for next generation Stage-5 spectroscopic surveys and potentially, future space-based imaging of extremely faint objects on missions such as the Habitable Worlds Observatory. Building upon the capability of the Skipper CCD to achieve deeply sub-electron noise floors, MAS CCDs utilize multiple floating-gate amplifiers along the serial register to increase the readout speed by a factor of the number of output nodes compared to a Skipper CCD. We introduce and experimentally demonstrate on a 16-channel prototype device new readout techniques that exploit the MAS CCD's floating-gate amplifiers to optimize the correlated double sampling by resetting once per line instead of once per pixel. With this new mode, we find an optimal filter to subtract the noise from the signal during read out. We also take advantage of the MAS CCD's structure to tune the read time by independently changing integration times for the signal and reference level. Together with optimal weighted averaging of the 16 outputs, these approaches enable us to reach a sub-electron noise of 0.9 e‑ rms pix‑1 at 19 μs pix‑1 for a single charge measurement per pixel—simultaneously giving a 30% faster readout time and 10% lower read noise compared to performance previously evaluated without these techniques.

Keywords: Astronomical detectors, CCD observation, Astronomical instrumentation
Synergy of Traditional Techniques and Convolutional Neural Networks for Classification of Cloudless Conditions by All-Sky Imagers. This work explores the capabilities of our two methods for the determination of cloudless conditions from All-Sky Imager (ASI) data. For the first time, it was demonstrated that the combination of a well-established traditional computer vision technique based on the calculation of a Clearness index and a new data-driven method, that utilizes Convolutional Neural Networks, leverages the benefits of both methods and suppresses their individual disadvantages. The developed tool is reliable and efficient, allowing us to study the occurrence of clear sky conditions over an excellent astronomical location at El Leoncito Observatory in Argentina throughout the years 2006–2023. It was found that seasonal variations in cloudiness conditions are present over long-term measurements of 18 yr. The detected variations are connected to changes in seasons with a minimum of averaged clear sky hours in January. The minima of long-term variations occurred in the years 2016 and 2023 which implies the potential usage of ASI data in climatological studies. In total, 40,250 clear sky hours were identified. On average per year, ∼75% of all observed hours were without clouds. These periods can be used for further ionospheric and space physics studies with data obtained via particular ASI narrowband filters. The presented data-driven approach will be used also for these planned studies as it demonstrated a high potential for automation of image processing from ASI instruments.

Keywords: Space research, All-sky cameras, Convolutional neural networks, Aeronomy, Cloud monitors, Astronomy data reduction
Electromagnetic Follow-up to Gravitational Wave Events with the UltraViolet EXplorer (UVEX). The Ultraviolet Explorer (UVEX) is expected to fly in 2030 and will have the opportunity—and the rapid near/far-ultraviolet (UV) capabilities—to glean unprecedented insight into the bright UV emission present in kilonovae like that of AT 170817gfo, the electromagnetic counterpart to binary neutron star merger GW170817. To do so, it will need to perform prompt target-of-opportunity observations following detection of binary neutron star mergers by the LIGO–Virgo–KAGRA gravitational observatories. We present initial simulations to develop UVEX target-of-opportunity strategies for such events and provide the community with detailed initial estimates of the prospects for and characteristics of UVEX target-of-opportunity observations following gravitational-wave events, considering fiducial scenarios for the fifth and sixth LIGO–Virgo–KAGRA observing runs. Additionally, in light of the relatively few binary neutron star mergers observed since GW170817, we consider variant target-of-opportunity strategies for UVEX to maximize scientific gain in the case of a lowered binary neutron star merger rate.

Keywords: Gravitational wave astronomy, Ultraviolet transient sources
Multi-wavelength Non-thermal Radiative Properties of Pulsar Wind Nebulae with Ages Around 10 kyr. With the advancement of detector technology, significant progress has been made in understanding Pulsar Wind Nebulae (PWNe) through multi-wavelength observations, particularly in the X-ray and TeV γ-ray bands. While young PWNe have been extensively studied, PWNe with ages around 10 kyr remain relatively underexplored. In this study, we investigate the radiative properties of four selected PWNe associated with the γ-ray sources HESS J1420-607, HESS J1418-609, HESS J1427-608, and HESS J1303-631 using a time-dependent electron population model. High-energy electrons and positrons are injected into the nebula, producing multi-wavelength non-thermal emission through synchrotron radiation and inverse Compton scattering. Based on comparisons with previous studies, we assume that four sources have not yet been compressed by the reverse shock, with estimated ages around 7–8 kyr. The injected particles follow a broken power-law distribution, with spectral indices consistent with previous studies. We find that the four nebulae are currently particle-dominated systems with magnetic field strengths ranging from a few μG to 10 μG, in agreement with theoretical expectations for PWNe at similar evolutionary stages. Our results support the scenario that all four sources originate with PWNe, as their multi-wavelength nonthermal emission can be reproduced with reasonable parameters.

Keywords: Non-thermal radiation sources, Centaur group
Simulating the Shaping of Point-symmetric Structures in the Jittering Jets Explosion Mechanism. We conduct three-dimensional hydrodynamical simulations of core-collapse supernovae by launching several pairs of jets into a collapsing core model and show that the jittering jets explosion mechanism (JJEM) can form a point-symmetric morphology that accounts for observed morphologies of about a dozen core-collapse supernovae (CCSN) remnants. Point-symmetric morphologies are composed of pairs of opposite structures around the center of the CCSN remnant. In the JJEM, the newly born neutron star launches several to a few tens of pairs of jets with stochastically varying directions, and these jets explode the star. In the simulations with the FLASH numerical code, we launch pairs of jets with varying directions, energies, opening angles, and durations into the massive stellar core and follow their evolution for about two seconds. We show that the jets form pairs of opposite filaments, clumps, bubbles, and lobes, namely, prominent point-symmetric morphologies. The interaction of the jets with the core leads to vigorous Rayleigh–Taylor instabilities and excites many vortices, which also shape clumps and filaments. Our results suggest that the JJEM could play a central role in the explosion mechanism of CCSNe; neutrino heating can boost the role of jets.

Keywords: Supernova remnants, Stellar jets, Massive stars, Core-collapse supernovae
Astrophysical Origins of Elemental Abundances in the LMC Inner Disk Stars. The unusual elemental abundance patterns in nearby dwarf galaxies offer eminent information for us to investigate the relationship of the nearby galaxies and the Milky Way (MW). We studied the observed elemental abundance patterns of the inner disk stars of the Large Magellanic Cloud (LMC) and found that the contributions of the main s-process, SNe Ia, and main r-process for the LMC inner disk stars are greater than those for the MW stars, while the dedications of the primary process and secondary processes are lower for LMC, which implies that, compared to MW, the stellar evolution environment of LMC lacks massive stars, while having more low-to-medium-mass stars. The lower α abundances of LMC inner disk stars are due to the lower contribution from the primary process to the LMC inner disk stars, whereas the lower Fe-peak abundances can be explained by the fewer donations from the primary and secondary processes of massive stars. The LMC and Fornax stars have a similar stellar abundance pattern: lower abundances of α- and Fe-peak elements, while higher abundances of heavy neutron-capture elements, such as Ba and Eu. The contributions of the main s-process, SNe Ia, main r-process for the LMC inner disk stars are lower than those of Fornax stars, while the contributions of the primary and secondary processes for LMC are higher. Compared to Fornax, the LMC stellar evolution environment nurtures more massive stars and fewer low-to-medium-mass stars.

Keywords: Stellar abundances, Galaxy evolution, Large Magellanic Cloud
General Analytic Solutions for Circumplanetary Disks during the Late Stages of Giant Planet Formation. Forming giant planets are accompanied by circumplanetary disks, as indicated by considerations of angular momentum conservation, observations of candidate protoplanets, and the satellite systems of planets in our Solar System. This paper derives surface density distributions for circumplanetary disks during the final stage of evolution when most of the mass is accreted. This approach generalizes previous treatments to include the angular momentum bias for the infalling material, more accurate solutions for the incoming trajectories, corrections to the outer boundary condition of the circumplanetary disk, and the adjustment of newly added material as it becomes incorporated into the Keplerian flow of the pre-existing disk. These generalizations lead to smaller centrifugal radii, higher column density for the surrounding envelopes, and higher disk accretion efficiency. In addition, we explore the consequences of different angular distributions for the incoming material at the outer boundary, with the concentration of the incoming flow varying from polar to isotropic to equatorial. These geometric variations modestly affect the disk surface density, but also lead to substantial modification to the location in the disk where the mass accretion rate changes sign. This paper finds analytic solutions for the orbits, source functions, surface density distributions, and the corresponding disk temperature profiles over the expanded parameter space outlined above.

Keywords: Exoplanet formation, Solar system formation, Protoplanetary disks
Spectral Structure of the Solar Inertial Motion from 12999 BC to 16998 AD. The solar inertial motion (SIM) reflects the dynamics of the planetary system around the Sun. To study and accurately model the frequency domain of the SIM is of great importance as any function of the orbits as a whole is expected to be spectrally coherent with it. This study proposes a comprehensive spectral model for accurately reconstructing the SIM frequencies using the orbital periodicities of the Jovian planets. Specifically, we utilize high-precision records of the SIM (from 12999 BC to 16998 AD) obtained from the latest JPL ephemeris files DE440 and DE441 to estimate the temporal sequences of the periods and lengths of the SIM orbital cycles. The 30,000 yr-long SIM records are used to evaluate SIM periodograms with the highest spectral resolution currently available. The obtained sharp spectra enabled the validation of our spectral model constructed using the orbital near-commensurabilities of Jupiter, Saturn, Uranus, and Neptune. We provide a brief overview of the primary mathematical properties of the proposed model and, in particular, we demonstrate that it can be conveniently represented and managed through the adoption of a vectorial formulation, which allows for the rapid calculation of each SIM periodicity. This formulation employs the synodic periods of each planet pair as constructors, in addition to the orbital period of a single planet (e.g., Jupiter alone). Thus, we demonstrate that the proposed spectral model accurately identifies the specific planetary origin of each frequency of the SIM, which are numerous, and illustrate that they are clustered around specific frequency values. Finally, we also show that these SIM frequency clusters are well centered around periods given by the harmonic model Pn ≈ 179/(n ‑ 1) yr (where n≥ 2 is the cluster order) up to at least the 20th harmonic and discuss the significance of some of the long millennial SIM periodicities.

Keywords: Astronomy data modeling, Ephemerides, Planetary alignment, Center of mass, The Sun, Solar-planetary interactions, Orbital resonances, Time series analysis, Solar motion
Thermal Evolution and Mass Loss on Short-period, Low-mass Planets During FU Orionis Outbursts. Ultra-short-period (USP) planets represent a unique class of exoplanets characterized by their tight orbits and relatively low masses, with some also exhibiting unusually high iron fractions. Previous work proposed a dynamical pathway wherein planets can migrate inward due to drag from sub-Keplerian gas during episodic FU Orionis (FU Ori) outbursts, an abrupt accretion phenomenon exhibited by young stellar objects, thereby potentially populating USP orbits. However, the implications of this migration process on the structural and compositional evolution of these planets remain unexplored. In this work, we model the response of a planet's surface material to the high disk temperatures characteristic of an FU Ori event and compute the fraction of an Earth-like planet's mass that will be lost due to vaporization and subsequent turbulent diffusion of gaseous molecules during the FU Ori event. We find that low-mass planets may lose a substantial fraction of their mantle mass during FU Ori events, potentially contributing to the observed prevalence of low-mass, iron-rich USP planets.

Keywords: Exoplanet structure, Exoplanet evolution, FU Orionis stars
An Alternate Method for Minimizing X<SUP>2</SUP>. In this paper, we describe an algorithm and associated software package (sfit_minimize) for maximizing the likelihood function of a set of parameters by minimizing χ2. The algorithm estimates the second derivative of the χ2 function using first derivatives of the function to be fitted and takes fractional, ϵ ≤ 1, steps at each iteration. The derivatives can also be used to calculate the uncertainties in each parameter. We test this algorithm against several standard minimization algorithms in SciPy.optimize.minimize() by fitting point lens models to light curves from the 2018 Korea Microlensing Telescope Network event database. We show that for fitting microlensing events, SFit works faster than the Nelder-Mead simplex method and is more reliable than the BFGS gradient method; we also find that the Newton-CG method is not effective for fitting microlensing events.

Keywords: Gravitational microlensing, Computational methods
K-DRIFT Preparation: Experimental Verification of an Observation Strategy for Accurate Dark-sky Flats. Despite its scientific importance, the low-surface-brightness universe has yet to be fully explored due to various systematic uncertainties that affect the achievable surface-brightness limit. Reducing these uncertainties requires very accurate data processing. The dark-sky flat is a widely used calibration frame for accurate flat-field correction, generated by combining the sky background from science images. However, the night sky will likely contain complex local fluctuations, thus may still lead to photometric errors in data calibrated with dark-sky flats. To address this concern, we conduct mock observations with semi-realistic sky simulation data and evaluate observation strategies to mitigate the impact of the fluctuating sky background. Our experiments consider two representative sky conditions (clear and dirty) and perform intensive comparative analysis on two observation methods (offset and rolling). Our findings suggest that the rolling dithering method, which incorporates the operation of camera rotation into conventional dithering, can provide more accurate dark-sky flats. Finally, we discuss the broader implications of this method through additional experiments examining several factors that may affect the imaging quality of observational data.

Keywords: Astronomical techniques, Sky brightness, Astronomy data reduction, Wide-field telescopes
Deep Learning to Improve the Discovery of Near-Earth Asteroids in the Zwicky Transient Facility. We present a novel pipeline that uses a convolutional neural network (CNN) to improve the detection capability of near-Earth asteroids (NEAs) in the context of planetary defense. Our work aims to minimize the dependency on human intervention of the current approach adopted by the Zwicky Transient Facility (ZTF). The target NEAs have a high proper motion of up to tens of degrees per day and thus appear as streaks of light in the images. We trained our CNNs to detect these streaks using three datasets: a set with real asteroid streaks, a set with synthetic (i.e., simulated) streaks and a mixed set, and tested the resultant models on real survey images. The results achieved were almost identical across the three models: 0.843 ± 0.005 in completeness and 0.820 ± 0.025 in precision. The bias on streak measurements reported by the CNNs was 1.84 ± 0.03 pixels in streak position, (0.817 ± 0.026)° in streak angle and ‑0.048 ± 0.003 in fractional bias in streak length (computed as the absolute length bias over the streak length, with the negative sign indicating an underestimation). We compared the performance of our CNN trained with a mix of synthetic and real streaks to that of the ZTF human scanners by analyzing a set of 317 streaks flagged as valid by the scanners. Our pipeline detected 80% of the streaks found by the scanners and 697 additional streaks that were subsequently verified by the scanners to be valid streaks. These results suggest that our automated pipeline can complement the work of the human scanners at no cost for the precision and find more objects than the current approach. They also prove that the synthetic streaks were realistic enough to be used for augmenting training sets when insufficient real streaks are available or exploring the simulation of streaks with unusual characteristics that have not yet been detected.

Keywords: Surveys, Near-Earth objects, Asteroids
A Fast Periodicity Detection Algorithm Sensitive to Arbitrary Waveforms. A reexamination of period-finding algorithms is prompted by new large-area astronomical sky surveys that can identify billions of individual sources having a thousand or more observations per source. This large increase in data necessitates fast and efficient period detection algorithms. In this paper, we provide an initial description of an algorithm that is being used for the detection of periodic behavior in a sample of 1.5 billion objects using light curves generated from Zwicky Transient Facility (ZTF) data. We call this algorithm "Fast Periodicity Weighting" (FPW), derived using a Gaussian Process formalism. Periodic sources in ZTF show a wide variety of waveforms, some quite complex, including eclipsing objects, sinusoidally varying objects also exhibiting eclipses, objects with cyclotron emission at various phases, and accreting objects with complex waveforms. A major advantage of the FPW algorithm is that it is sensitive to a broad range of waveforms. We describe the FPW algorithm and its application to ZTF, and provide efficient code for both CPU and GPU.

Keywords: Surveys, Periodic variable stars, Algorithms, Fast Fourier transform
Tilsotua: Reproducing Slitmask Sky Positions for use with the LRIS Multislit Archive. We present tilsotua, a code that calculates sky positions of the slits from Low-Resolution Imaging Spectrograph (LRIS) slitmasks used in multislit observations. Raw data for the Keck/LRIS spectrograph does not include information about the sky positions of the slitmask targets, making it difficult to use beyond the scope of the original programs. tilsotua translates slit coordinates from the mask design files in the mask milling machine frame to sky coordinates. tilsotua also shifts the original input astrometry to modern frames using the objects targeted by mask alignment boxes. This can be applied to the archived mask design files at the Lick Observatory Archive. We demonstrate that the final reconstructed slit positions are accurate to  0.″14  (rms) across the set of archived masks based on a comparison of our calculated mask alignment box coordinates with Gaia astrometric positions of the likely alignment objects. We make available the tilsotua code, archived mask files, and slit positions of the historical masks for the community to maximize the science from Keck/LRIS data in the Keck Observatory Archive.

Keywords: Software documentation, Publicly available software, Astronomy software, Spectroscopy