Sazuna/UAT_keywords huggingface dataset:
Secondary Standards in the UKIRT Faint Standard Fields. We present precise J- and K-band photometric measurements for 128 near-infrared (NIR) secondary standard stars, located in the 19 United Kingdom Infrared Telescope/Maunakea Observatories (UKIRT/MKO) primary faint standard fields. The data were collected over more than 50 nights, covering a decade of observations between 2008 and 2018 at the ESO La Silla Observatory, using the New Technology Telescope equipped with the SOFI NIR camera. Presented magnitudes are calibrated onto the MKO photometric system. The J- and K-band magnitudes range from 10 to 15.8 mag, with median values of  J∼  = 13.5 mag and  K∼  = 13 mag. The selection process ensured high photometric quality, with a precision better than 0.01 mag for all stars. The catalog excludes stars with close neighbors, high proper motion, or variable stars. Using these fields for standardization can improve the precision and accuracy of photometric calibrations without increasing the observational time cost.

Keywords: Astronomical methods
Toward a Comprehensive Grid of Cepheid Models with MESA. II. Impact of Physical and Numerical Assumptions on Elemental Abundances. Modern tools for modeling stellar evolution, such as the Modules for Experiments in Stellar Astrophysics, offer state-of-the-art implementations of stellar theories. However, this parametric approach introduces many free parameters that are often not constrained by observations. This is particularly important for evolved stars, like classical Cepheids, because uncertainties increase with evolution time. In previous work, we studied the effect of varying microphysics, including solar abundance mixtures, nuclear networks, atmosphere models, mixing-length prescriptions, treatments of convective boundaries, and numerical setup on evolutionary tracks. Here, we extend this analysis to the surface abundances of the dominant elements H, He, C, N, O, Ne, and Mg. We establish a reference model and 22 variants for each mass (M) and metallicity (Z), evolving them from the zero-age main sequence to central helium exhaustion. Masses between 2─8 M⊙ and metallicities Z = 0.0014, 0.004, and 0.014 are explored, spanning the range of classical Cepheids. Both canonical and overshooting models are computed and compared. We find that uncertainties in the surface abundances are generally small, arising mainly from variations in the depth of the convective envelope during the first dredge up. The size of the convective envelope is sensitive to many aspects, including mass and metallicity. The central C/O ratio, relevant for white dwarf evolution, can vary by ∼0.15, driven largely by convective boundary treatments or by modifying the 12C(α, γ)16O reaction rate during helium burning. Surface and central abundances for the considered models at several benchmark points during the evolution are provided online.

Keywords: Cepheid variable stars, Stellar evolutionary models, Chemical abundances
LSTM-MDNz: Estimating Quasar Photometric Redshifts with an LSTM-augmented Mixture Density Network. Quasar photometric redshifts are essential for studying cosmology and large-scale structures. However, their complex spectral energy distributions cause significant redshift─color degeneracy, limiting the accuracy of traditional methods. To overcome this, we introduce long short-term memory (LSTM)-MDNz, a novel end-to-end deep learning model combining LSTM networks with mixture density networks (MDNs). The model directly uses multiband photometric fluxes and associated errors as wavelength-ordered sequential inputs, eliminating the need for manual feature engineering while enabling simultaneous point estimation and probability density function (pdf) prediction of quasar redshifts. We integrate data from four major sky surveys—Sloan Digital Sky Survey (SDSS), DESI-Legacy Imaging Surveys, Wide-field Infrared Survey Explorer (WISE), and Galaxy Evolution Explorer—to assemble a sample of over 550,000 spectroscopically confirmed quasars (0 ≤ zspec ≤ 5) across 14 ultraviolet to infrared bands for model training and testing. Experimental results show that using all 14 bands yields optimal performance, with a normalized median absolute deviation (σNMAD) of 0.037 and an outlier rate (fout) of 3.5% on the test set. These values represent reductions of 29% and 56%, respectively, compared to the commonly adopted SDSS+WISE band set. Probability integral transform and continuous ranked probability score analyses confirm that the predicted pdfs align closely with the true redshift distribution. Band-ablation experiments further highlight the essential role of ultraviolet and infrared data in alleviating color degeneracy and reducing systematic bias. This study demonstrates the effectiveness of multiband fusion in improving quasar photo-z accuracy and offers a ready-to-use estimation framework for future surveys like LSST, CSST, and Euclid.

Keywords: Computational astronomy, Sky surveys, Astronomy data analysis, Astrostatistics, Photometry, Redshift surveys
Unveiling the Chemical Complexity and C/O Ratio of the HD 163296 Protoplanetary Disk: Constraints from Multiline ALMA Observations of Organics, Nitriles, and Sulfur-bearing and Deuterated Molecules. The physical and chemical conditions within a protoplanetary disk play a crucial role in determining its chemical composition, which is subsequently inherited by any forming planets. To probe these conditions, high-resolution molecular line observations, coupled with modeling, are essential. In this study, we investigate the chemistry of the nearby, massive, and relatively line-rich protoplanetary disk around HD 163296 using high-resolution observations from the Atacama Large Millimeter/submillimeter Array (ALMA) across Bands 3, 4, 6, and 7. We constrain the disk-averaged and radial distributions of column density and excitation temperature for the detected molecules using the new retrieval code DRive. The disk chemistry is modelled using the astrochemical code PEGASIS, with variations in the initial elemental C/O ratio. Our modelling, informed by molecular observations of HCO+, DCO+, HCN, DCN, CS, HC3N, H2CO, CH3OH, HNCO, and NH2CHO, allows us to place strong constraints on the C/O ratio, with a best-fit value of 1.1 that is broadly consistent with previous estimates. We present the highest-resolution DCO+ emission map of this disk to date, revealing triple-ringed chemical substructures that closely align with the dust continuum rings. Additionally, our results provide the first and most stringent upper limits on the column densities of NH2CHO and HNCO in this protoplanetary disk, measured at &lt;7 × 1011 cm−2 and &lt;1 × 1011 cm−2, respectively. Our chemical models suggest that NH2CHO and HNCO predominantly form on grain surfaces within the disk. However, physicochemical desorption mechanisms are inefficient at releasing these species into detectable gas-phase abundances, yet they remain promising targets for future ALMA observations.

Keywords: Protoplanetary disks, Planet formation, Astrochemistry
A Core-collapse Supernova Neutrino Parameterization with Enhanced Physical Interpretability. We introduce a novel parameterization of supernova neutrino energy spectra with a clear physical motivation. Its central parameter, τ(t), quantifies the characteristic thermal-diffusion area during the explosion. When applied to the historic SN 1987A data, this parameterization yields statistically significant fits and provides robust constraints on the unobserved low-energy portion of the spectrum. Beyond this specific application, we demonstrate the model's power on a suite of 3D core-collapse supernova simulations, finding that the temporal evolution of τ(t) distinctly separates successful from failed explosions. Furthermore, we constrain the progenitor mass of SN 1987A to approximately 19 solar masses by applying a smoothed isotonic regression, while noting the sensitivity of this estimate to observational uncertainties. Moreover, in these simulations, τ(t) and the gravitational-wave strain amplitude display a strong, synergistic coevolution, directly linking the engine's energetic evolution to its geometric asymmetry. This implies that the thermodynamic state of the explosion is not only imprinted on the escaping neutrino flux but also recorded in the shape of the energy spectrum. Our framework therefore offers a valuable tool for decoding the detailed core dynamics and multimessenger processes of future Galactic supernovae.

Keywords: Supernova neutrinos, Core-collapse supernovae
Assessing the Effects of Composition and Surface Roughness on the Photopolarimetric Response of Planetary Regoliths. This study is part of an ongoing project in which we experimentally examine the effect of composition (refractive index) and surface roughness on the scattering matrix elements of a set of well-characterized rough regolith simulants. A set of four cylindrical Mars regolith simulants with controlled degrees of porosity and surface roughness is studied. Photopolarimetric measurements, spanning scattering angles from 94° to 177°, were conducted at a wavelength of 488 nm at the Instituto de Astrofísica de Andalucía Cosmic Dust Laboratory. These results are compared with those previously obtained at 640 nm. The higher absorption of the Mars simulants at 488 nm compared to 640 nm produces a significant effect on all elements of the scattering matrix. The trends previously observed in the diagonal elements of the scattering matrix and in the albedo as a function of surface roughness remain unaffected by the differences in refractive indices at both wavelengths. The comparison with the previous study enables the investigation of sample reddening across the scattering-angle range, with a trend also observed between surface roughness and reddening. Moreover, within our measured angular range, the effect of absorption is consistent with Umov's law, whereas the effects of surface roughness do not appear to support its validity. Nearly all samples exhibit a shallow negative polarization branch.

Keywords: Regolith, Planetary surfaces, Polarimetry, Optical constants (Dust)
Comprehensive Analyses of Cumulative Frequency Distributions for Solar X-Ray Flares. We investigate the temporal evolution of cumulative flare frequency (CFF) distributions using solar X-ray data (0.5─4.0 Å) from Geostationary Operational Environmental Satellites between 1974 and 2020. Beyond the conventional power-law fitting, we introduce a novel modelling approach based on the two-phase exponential association (TPEA) function. This method enables a more robust characterization of distribution shapes and allows for a precise derivation of the power-law index (∝) from the linear component of the model. Our analysis reveals that CFF distributions vary in both structure and scale over time. While the frequency axis reflects clear 11 yr solar activity cycle modulations, we identify a secondary, long-term variation in flare energy that is independent of the activity cycle. The ∝ values derived from the TPEA model exhibit sinusoidal oscillations superimposed on an increasing long-term trend, with occasional values exceeding the critical threshold of ∝ = 2. These findings suggest that both the frequency and energy characteristics of solar flares evolve systematically, and that flare energetics may follow a separate, longer-term modulation beyond the sunspot cycle. This study provides a refined method for tracking flare activity and uncovers new insights into the long-term variability of solar magnetic phenomena.

Keywords: Solar flares
Fast Deep Learning─based Imaging for Synthetic Aperture Array: Application to DART. DAocheng Radio Telescope (DART) is a radio synthetic aperture array consisting of 313 antennas, dedicated to monitoring solar activities and observing cosmic radio sources. To meet the real-time demands of interferometric brightness temperature imaging, we propose a deep learning─based fast-imaging method (DLSI). This method takes dynamically projected baselines and visibility functions as joint inputs, reconstructing brightness temperature images through a single forward pass. Extensive experiments demonstrate that the DLSI achieves imaging quality on DART solar observation data comparable to traditional methods such as gridding combined with CLEAN while reducing computational time by 3 orders of magnitude. Furthermore, under 15%─40% random antenna failure scenarios, the network maintains robust imaging performance, demonstrating exceptional adaptability to hardware malfunctions and strong generalization capability.

Keywords: Aperture synthesis, Neural networks, Brightness temperature, Radio astronomy, Interferometry
A TimesNet-based Real-time Forecasting System for the F10.7 Index Using DRAO and Chinese Langfang Datasets. In this paper, we construct the DRAO univariate dataset, the DRAO multivariate dataset, and the Chinese Langfang dataset. We develop and compare five deep learning models (TimesNet, iTransformer, PatchTST, N-Beats, BiGRU) and a benchmark artificial neural network (ANN) model to predict the F10.7 index. We study the impact of different feature combinations on the performance of the recommended TimesNet model. Furthermore, we develop a real-time forecasting system for the F10.7 index, incorporating both univariate and multivariate TimesNet models. During the same period, we compare F10.7 prediction performance between our system and that of four foreign institutions (British Geological Survey (BGS), SWPC, Collecte Localisation Satellites (CLS), DRAO). We conduct daily averaged and hourly resolution forecasting using the Langfang dataset. To our knowledge, we establish the first TimesNet-based framework for F10.7 prediction, advancing hourly resolution F10.7 forecasting for the first time. The main results are as follows. (1) The univariate TimesNet model achieves superior prediction performance on the first to the 27th day of forecasting, outperforming both four deep learning models and the ANN model. With the increase in the prediction days, the prediction performance of the six models all shows a downward trend. (2) The multivariate TimesNet-FIAC model, using optimal feature combinations, outperforms the univariate TimesNet-F model. (3) In short-term prediction, TimesNet-FIAC within our system surpasses four foreign institutions. On the first forecasting day, its root mean square error, mean absolute error, and mean absolute percentage error decrease by 15.06%, 18.54%, and 20.90% compared to BGS, and by 3.54%, 10.21%, and 14.94% compared to CLS. (4) On the Langfang dataset, TimesNet-F demonstrates superior generalization in daily averaged short-term forecasting, and maintains good and stable performance in hourly resolution short-term prediction.

Keywords: Solar radio emission
GMIMS-DRAGONS: A Faraday Depth Survey of the Northern Sky Covering 350─1030 MHz. Polarized synchrotron emission at meter to centimeter wavelengths provides an effective tracer of the Galactic magnetic field. Calculating Faraday depth, the most useful parameter for mapping the line-of-sight magnetic field, requires observations covering wide frequency bands with many channels. As part of the Global Magneto-Ionic Medium Survey (GMIMS), we have observed polarized emission spanning 350─1030 MHz over the northern sky, in the declination range −20° ≤ δ ≤ 90°. We used the 15 m telescope at the Dominion Radio Astrophysical Observatory (DRAO), equipped to receive orthogonal circular polarizations, with the Onsala Space Observatory band 1 feed developed for the SKA Project. Angular resolution varies across the band from 1 .° 3 to 3 .° 6. A digital spectrometer provided 42 kHz frequency resolution. Data were taken with the telescope moving rapidly in azimuth and are absolutely calibrated in intensity. Approximately 25% of the data were lost due to radio-frequency interference. The resolution in Faraday depth is ∼6 rad m−2, and features as wide as ∼38 rad m−2 are represented. The median sensitivity of the Faraday depth cube is 11 mK. Approximately 55% of sight lines in this survey show Faraday complexity. This dataset, called "DRAO GMIMS of the Northern Sky," is the first to probe Faraday depth of the northern sky in its frequency range and will support many scientific investigations. The data will be used to calibrate surveys with higher angular resolution, particularly Galactic foreground maps from the Canadian Hydrogen Intensity Mapping Experiment, and to provide information on large structures for aperture-synthesis telescopes, particularly the DRAO Synthesis Telescope. The data are available through the Canadian Astronomy Data Centre.

Keywords: Galaxy magnetic fields, Sky surveys, Milky Way magnetic fields, Radio telescopes, Single-dish antennas, Interstellar medium, Polarimetry
NEXUS Early Data Release: NIRCam Imaging and WFSS Spectroscopy from the First (Partial) Wide Epoch. We present the early data release of the multicycle JWST-NEXUS treasury program (2024─2028), which includes NIRCam imaging and WFSS observations from the first (partial) NEXUS-Wide epoch covering the central 100 arcmin2 of the NEXUS field, located near the north ecliptic pole and within the Euclid Ultra-Deep Field. We release reduced NIRCam mosaics (F090W, F115W, F150W, F200W, F356W, and F444W), photometric source catalogs, as well as preliminary WFSS spectra (in F322W2 and F444W) for the subset of bright sources (F356W &lt;21 mag or F444W &lt;21 mag). These observations fully cover the NEXUS-Deep area, and anchor the long-term baseline of the program. These data will be used for initial target selection for the NIRSpec/Multi-Object Spectroscopy (MOS) starting from 2025 June. The NIRCam imaging reaches depths of 27.4─28.2 (AB) mag in F090W─F444W. Upcoming NEXUS-Wide epochs will expand the area to the full ∼400 arcmin2, and improve the NIRCam exposure depths in the Wide tier by a factor of 3. In addition, this central region will be repeatedly covered by the NEXUS-Deep observations (NIRCam imaging and NIRSpec/MOS PRISM spectroscopy) over 18 epochs with a ∼2 month cadence. We demonstrate the data quality of the first NEXUS observations, and showcase some example science cases enabled by these data.

Keywords: Brown dwarfs, Surveys, Active galactic nuclei, High-redshift galaxies, Supernovae
New Single-lined Spectroscopic Binaries Identified from the LAMOST Medium-resolution Spectroscopic Survey. A typical single-lined spectroscopic binary (SB1) consists of two stars with almost the same age but markedly different masses and physical properties. SB1s are essential for obtaining the statistical properties of stars and constraining stellar evolutionary models, particularly when orbital parameters are well determined. In this study, we first carry out a data-cleaning step on a sample of LAMOST Medium-Resolution Spectroscopic Survey stars with a sufficient number of observations and perform an F2 test, obtaining 7775 radial velocity variables. After removing false positives and crossmatching with variable and double-lined spectroscopic binary (SB2) catalogs, we exclude known astrophysical variables and SB2s, leaving 6106 SB1 candidates. We estimate initial periods using the Heck─Manfroid─Mersch method combined with Monte Carlo simulations and then fit each source with both an orbital model and a trend model, selecting between them via the Snedecor F-test of nested models. For orbital models, we accept the least-χ2 solution if it satisfies F2 &lt; 3.1, s &gt; 10, phase_gap_max &lt; 0.3, σv/K &lt; 0.25 and passes the Markov Chain Monte Carlo─based robustness tests. For trend cases, we discard zeroth-order fits and require F2 &lt; 3.1. In total, we obtain 623 accepted solutions, of which 337 SB1s are new relative to existing catalogs.

Keywords: Spectroscopic binary stars, Radial velocity, Astronomy data analysis, Orbit determination
Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. XV. Reverberation Mapping of Mg II Emission Lines. As the 15th paper in a series reporting on a large reverberation mapping (RM) campaign of super-Eddington accreting massive black holes (SEAMBHs) in active galactic nuclei (AGNs), we present the results of measurements of the Mg II lines in 18 SEAMBHs monitored spectroscopically from 2017 to 2024. Among these, the time lags of Mg II have been successfully determined for eight of the 18 objects, thereby expanding the current Mg II RM sample, particularly at higher accretion rates. By incorporating measurements of the line widths, we determine the masses of their central supermassive black holes. Based on these new measurements, we update the relation between the Mg II radius and the monochromatic luminosity at 3000 Å (RMgII─L3000 relation), yielding a slope of 0.24 ± 0.03, which is slightly shallower than, yet still consistent with, previously reported values. Similar to the Hβ lines, the Mg II time lags in SEAMBHs are shorter than those of AGNs with normal accretion rates at comparable luminosities. The deviation of AGNs from the best-fit RMgII─L3000 relation shows a strong correlation with the accretion rate, while no significant correlation is found between the deviation and the flux ratio of UV iron to Mg II.

Keywords: Supermassive black holes, Reverberation mapping, Active galactic nuclei, Quasars
A Characterization of JWST MIRI Detector Persistence and Implications for High-contrast Imaging. The JWST MIRI detector exhibits a flux-deficit persistence, but its timescales and impacts remain largely uncharacterized, particularly at the longest imaging wavelengths. In this study, we analyze full-field MIRI imager observations at 21 μm (F2100W) to quantify detector persistence following a saturation event by a bright (K = 5.65 mag) nearby (8.12 ± 0.04 pc) mid─M dwarf star, IRAS 21500+5903. Unlike typical persistence that appears as excess flux, this effect presents as a flux deficit in pixels previously illuminated by the saturating or near-saturating source. We measure persistence at two postsaturation epochs: shortly after saturation (11.6 minutes) and an hour later (1.39 hr). Immediately after the saturation event, we detect a persistence level of 1.69% ± 0.10%. By fitting a Bayesian exponential decay model to the two epochs, we estimate that persistence decreases to one-tenth of its initial value after  5.16−0.94+1.49 hr. We examine the implications of persistence for MIRI high-contrast imaging using the imager (not coronagraphy). Specifically, we discuss how MIRI detector persistence can produce false-positive exoplanet signals in direct imaging surveys, as well as degrade point-spread function subtraction, particularly at small inner-working angles. We also outline mitigation strategies to avoid these impacts in future observations.

Keywords: James Webb Space Telescope, Astronomical instrumentation, Infrared telescopes, Infrared photometry