Sazuna/UAT_keywords huggingface dataset:
Weighted Stacking of Radio Images Affected by Noise and Interfering Signals. We implement an algorithm based on the weighted stacking of astronomical images that can combine different observations of the same region of the sky removing the interfering signals. We develop a C++ code that takes as input a set of spectral cubes and computes the local weights of the intensity for each pixel of every channel. The weights are calculated as the inverse variance of the nearby pixels and are used to compute the weighted merge of the input files. Astronomical sources, present in all cubes, are preserved by the weighted average. However, interfering signals, present in specific cubes and a certain frequency range, are down-weighted in the average and removed from the output spectral cube. We present the results obtained by analyzing simulated spectral cubes containing astronomical sources, noise, and a random set of interferences of different intensities and spectral occupations. The performance of the algorithm is evaluated by comparing the output result with the input sky-model image. Finally, we present the results obtained by applying the method to a set of real data consisting of observations of the Andromeda galaxy, Messier 31 (M31), at 6.6 GHz obtained with the Sardinia Radio Telescope.

Keywords: Radio spectroscopy, Interdisciplinary astronomy, Radio astronomy, Astronomical methods
Virial Black Hole Masses for Active Galactic Nuclei behind the Magellanic Clouds. We use the spectroscopic data collected by the Magellanic Quasars Survey (MQS) and the photometric V- and I-band data from the Optical Gravitational Lensing Experiment (OGLE) to measure the physical parameters for active galactic nuclei (AGNs) located behind the Magellanic Clouds. The flux-uncalibrated MQS spectra were obtained with the 4 m Anglo-Australian Telescope and the AAOmega spectroscope (R = 1300) in a typical ∼1.5 hr visit. They span a spectral range of 3700–8500 Å and have signal-to-noise ratios in a range of 3–300. We report the discovery and observational properties of 161 AGNs in this footprint, which expands the total number of spectroscopically confirmed AGNs by MQS to 919. After the conversion of the OGLE mean magnitudes to the monochromatic luminosities at 5100, 3000, and 1350 Å, we were able to reliably measure the black hole masses for 165 out of 919 AGNs. The remaining physical parameters we provide are the bolometric luminosities and the Eddington ratios. A fraction of these AGNs have been observed by the OGLE survey since 1997 (all of them since 2001), enabling studies of correlations between the variability and physical parameters of these AGNs.

Keywords: Supermassive black holes, Active galactic nuclei, Quasars
Design and Performance of a 30/40 GHz Diplexed Focal Plane for the BICEP Array. We demonstrate a wideband diplexed focal plane suitable for observing low-frequency foregrounds that are important for cosmic microwave background polarimetry. The antenna elements are composed of slotted bowtie antennas with 60% bandwidth that can be partitioned into two bands. Each pixel is composed of two interleaved 12 × 12 pairs of linearly polarized antenna elements forming a phased array, designed to synthesize a symmetric beam with no need for focusing optics. The signal from each antenna element is captured in-phase and uniformly weighted by a microstrip summing tree. The antenna signal is diplexed into two bands through the use of two complementary, six-pole Butterworth filters. This filter architecture ensures a contiguous impedance match at all frequencies, and thereby achieves minimal reflection loss between both bands. Subsequently, out-of-band rejection is increased with a bandpass filter and the signal is then deposited on a transition-edge sensor bolometer island. We demonstrate the performance of this focal plane with two distinct bands, 30 and 40 GHz, each with a bandwidth of ∼20 and 15 GHz, respectively. The unequal bandwidths between the two bands are caused by an unintentional shift in diplexer frequency from its design values. The end-to-end optical efficiency of these detectors is relatively modest, at 20%–30%, with an efficiency loss due to an unknown impedance mismatch in the summing tree. Far-field beam maps show good optical characteristics, with edge pixels having no more than ∼5% ellipticity and ∼10%–15% peak-to-peak differences for A–B polarization pairs.

Keywords: Polarimeters, CMBR detectors, Astronomical instrumentation
Changing-look Active Galactic Nuclei. I. Tracking the Transition on the Main Sequence of Quasars. This paper is the first in a series of papers that prepare and analyze spectral and other properties for a database of already-discovered changing-look active galactic nuclei (CL AGNs). Here we focus on the spectral fitting and analysis of broad emission lines in a sample of 93 CL AGNs collected from the literature with existing Sloan Digital Sky Survey (SDSS)/Baryon Oscillation Spectroscopic Survey (BOSS)/extended-BOSS spectroscopy where the Hβ emission-line profile does not completely disappear in any epochs. Additionally, we have gathered older/newer spectral epochs from all the available SDSS data releases to make the database more complete. We use PYQSOFIT and perform a homogeneous spectral decomposition of all of our SDSS spectra and tabulate the AGN continuum and emission-line properties per epoch per source, chronologically. This further allows us to categorize the sources in our sample as Turn-On or Turn-Off and subsequently check for repeated occurrences of such phases. We then estimate the black hole mass (M BH) and the Eddington ratio (λ Edd) per epoch per source where the required parameters are available and well estimated. We demonstrate the movement of the source in the M BH–λ Edd plane, allowing us to check for systematic changes in the source's fundamental properties. We then track their transition along the optical plane of the Eigenvector 1 schema and categorize sources that either stay within the same population (A or B) or make an interpopulation movement as a function of spectral epoch. We also test the Balmer decrement (Hα/Hβ) of a subset of our sample of CL AGNs as a function of time and AGN luminosity.

Keywords: Supermassive black holes, Quasars, Active galactic nuclei, Spectroscopy, Catalogs
The ZTF Source Classification Project. III. A Catalog of Variable Sources. The classification of variable objects provides insight into a wide variety of astrophysics ranging from stellar interiors to galactic nuclei. The Zwicky Transient Facility (ZTF) provides time-series observations that record the variability of more than a billion sources. The scale of these data necessitates automated approaches to make a thorough analysis. Building on previous work, this paper reports the results of the ZTF Source Classification Project (SCoPe), which trains neural network and XGBoost (XGB) machine-learning (ML) algorithms to perform dichotomous classification of variable ZTF sources using a manually constructed training set containing 170,632 light curves. We find that several classifiers achieve high precision and recall scores, suggesting the reliability of their predictions for 209,991,147 light curves across 77 ZTF fields. We also identify the most important features for XGB classification and compare the performance of the two ML algorithms, finding a pattern of higher precision among XGB classifiers. The resulting classification catalog is available to the public, and the software developed for SCoPe is open source and adaptable to future time-domain surveys.

Keywords: Astronomy databases, Classification, Neural networks, Surveys, Astronomy software, Cloud computing, Computational methods, Variable stars, GPU computing, Algorithms, Catalogs, Intrinsic variable stars
Presupernova Evolution and Explosive Nucleosynthesis of Rotating Massive Stars. II. The Supersolar Models at [Fe/H] = 0.3. We present an extension of the set of models published in Limongi &amp; Chieffi (2018) at metallicity 2 times solar, i.e., [Fe/H] = 0.3. The key physical properties of these models at the onset of core collapse are mainly due to the higher mass loss triggered by the higher metallicity: the supersolar metallicity (SSM) models reach core collapse with smaller He- and CO-core masses, while the amount of 12C left by the central He burning is higher. These results are valid for all the rotation velocities. The yields of the neutron-capture nuclei expressed per unit mass of oxygen (i.e., the X/O) are higher in the SSM models than in the SM ones in the nonrotating case, while the opposite occurs in the rotating models. The trend shown by the nonrotating models is the expected one, given the secondary nature of the neutron-capture nucleosynthesis. Vice versa, the counterintuitive trend obtained in the rotating models is the consequence of the higher mass loss present in the SSM models, removes the H-rich envelope faster than in the SM models while the stars are still in central He burning, dumping out the entanglement (activated by the rotation instabilities) and therefore conspicuous primary neutron-capture nucleosynthesis.

Keywords: Stellar rotation, Stellar nucleosynthesis, Massive stars, Core-collapse supernovae
Infrared Properties of Carbon Stars in Our Galaxy. We explore the characteristics of carbon stars within our Galaxy through a comprehensive analysis of observational data spanning visual and infrared (IR) bands. Leveraging data sets from IRAS, the Infrared Space Observatory, Akari, the Midcourse Space Experiment, the Two Micron All Sky Survey, the Wide-field Infrared Survey Explorer (WISE), Gaia DR3, AAVSO, and the SIMBAD object database, we conduct a detailed comparison between the observational data and theoretical models. To facilitate this comparison, we introduce various IR two-color diagrams (2CDs), IR color–magnitude diagrams (CMDs), and spectral energy distributions (SEDs). We find that the CMDs, which utilize the latest distance and extinction data from Gaia DR3 for a substantial number of carbon stars, are very useful for distinguishing carbon-rich asymptotic giant branch (CAGB) stars from extrinsic carbon stars that are not in the AGB phase. To enhance the accuracy of our analysis, we employ theoretical radiative transfer models for dust shells around CAGB stars. These theoretical dust shell models demonstrate a commendable ability to approximate the observations of CAGB stars across various SEDs, 2CDs, and CMDs. We present the infrared properties of known pulsating variables and explore the infrared variability of the sample stars by analyzing WISE photometric data spanning the last 14 years. Additionally, we present a novel catalog of CAGB stars, offering enhanced reliability and a wealth of additional information.

Keywords: Carbon stars, Infrared astronomy, Asymptotic giant branch stars, Long period variable stars, Radiative transfer, Circumstellar dust
Accurate Infrared Line Lists for 20 Isotopologues of CS<SUB>2</SUB> at Room Temperature. To facilitate atmospheric and spectroscopic studies of carbon disulfide, or CS2, in both planetary and exoplanetary atmospheres, we adopt the "Best Theory + Reliable High-resolution Experiment" algorithm to generate semiempirical IR line lists for the 20 most abundant CS2 isotopologues, denoted as Ames-296K. The IR lists are computed using the Ames-1 potential energy surface, refined using the experimental transition set and an ab initio dipole moment surface fitted from CCSD(T)/aug-cc-pV(T/Q/5+d)Z dipoles extrapolated to a one-particle basis set limit. The IR lists cover the range of 0–10,000 cm‑1, with an S 296K cutoff at 10‑31 cm‑1/molecule·cm‑2 (abundance included). A "natural" IR line list at 296 K includes about 10 million lines of the 20 isotopologues, with their intensities scaled by the corresponding abundances. The zero-point energy, partition functions, and abundances are reported for each isotopologue. The energy levels in the global effective Hamiltonian model for 12C32S2 are adopted to improve the line position accuracy. This new IR list for the main isotopologue is denoted as A+I.296K. Reliable HITRAN2020 line positions are also utilized to improve the accuracy of the 32S12C34S, 32S12C33S, and 32S13C32S isotopologue line lists. The final composite line list is validated against Pacific Northwest National Laboratory experimental cross sections, showing excellent agreement. The agreement supports the quality of the composite line list and the power of synergy between experiment and theory. The new data are proposed for use in updating and expanding the CS2 data in HITRAN and other high-resolution IR databases. Supplementary files are available in Zenodo and AHED.

Keywords: Exoplanet atmospheric composition , Spectral line lists, Isotopic abundances, Infrared spectroscopy, Potential energy surfaces, Laboratory astrophysics, Molecular spectroscopy, Astrochemistry, Far infrared astronomy, Quantum-chemical calculations, Infrared observatories
CAMEL. II. A 3D Coronal Mass Ejection Catalog Based on Coronal Mass Ejection Automatic Detection with Deep Learning. Coronal mass ejections (CMEs) are major drivers of geomagnetic storms, which may cause severe space weather effects. Automating the detection, tracking, and three-dimensional (3D) reconstruction of CMEs is important for operational predictions of CME arrivals. The COR1 coronagraphs on board the Solar Terrestrial Relations Observatory spacecraft have facilitated extensive polarization observations, which are very suitable for the establishment of a 3D CME system. We have developed such a 3D system comprising four modules: classification, segmentation, tracking, and 3D reconstructions. We generalize our previously pretrained classification model to classify COR1 coronagraph images. Subsequently, as there are no publicly available CME segmentation data sets, we manually annotate the structural regions of CMEs using Large Angle and Spectrometric Coronagraph C2 observations. Leveraging transformer-based models, we achieve state-of-the-art results in CME segmentation. Furthermore, we improve the tracking algorithm to solve the difficult separation task of multiple CMEs. In the final module, tracking results, combined with the polarization ratio technique, are used to develop the first single-view 3D CME catalog without requiring manual mask annotation. Our method provides higher precision in automatic 2D CME catalog and more reliable physical parameters of CMEs, including 3D propagation direction and speed. The aforementioned 3D CME system can be applied to any coronagraph data with the capability of polarization measurements.

Keywords: Solar activity, Astronomy data analysis, Solar coronal mass ejections
TREASUREHUNT: Transients and Variability Discovered with HST in the JWST North Ecliptic Pole Time-domain Field. The James Webb Space Telescope (JWST) North Ecliptic Pole (NEP) Time-domain Field (TDF) is a &gt;14' diameter field optimized for multiwavelength time-domain science with JWST. It has been observed across the electromagnetic spectrum both from the ground and from space, including with the Hubble Space Telescope (HST). As part of HST observations over three cycles (the "TREASUREHUNT" program), deep images were obtained with the Wide Field Camera on the Advanced Camera for Surveys in F435W and F606W that cover almost the entire JWST NEP TDF. Many of the individual pointings of these programs partially overlap, allowing an initial assessment of the potential of this field for time-domain science with HST and JWST. The cumulative area of overlapping pointings is ∼88 arcmin2, with time intervals between individual epochs that range between 1 day and 4+ yr. To a depth of m AB ≃ 29.5 mag (F606W), we present the discovery of 12 transients and 190 variable candidates. For the variable candidates, we demonstrate that Gaussian statistics are applicable and estimate that ∼80 are false positives. The majority of the transients will be supernovae, although at least two are likely quasars. Most variable candidates are active galactic nuclei (AGNs), where we find 0.42% of the general z ≲ 6 field galaxy population to vary at the ∼3σ level. Based on a 5 yr time frame, this translates into a random supernova areal density of up to ∼0.07 transients arcmin−2 (∼245 deg−2) per epoch and a variable AGN areal density of ∼1.25 variables arcmin−2 (∼4500 deg−2) to these depths.

Keywords: AGN host galaxies, Transient sources, HST photometry, Time domain astronomy, Supernovae
A Blueprint for the Milky Way's Stellar Populations. V. 3D Local Dust Extinction. Using a grid of empirically calibrated synthetic spectra developed in our previous study, we construct an all-sky 3D extinction map from the large collection of low-resolution XP spectra in Gaia DR3. Along each line of sight, with an area ranging from 0.2 to 13.4 deg2, we determine both the reddening and metallicity of main-sequence stars and model the foreground extinction up to approximately 3 kpc from the Sun. Furthermore, we explore variations in the total-to-selective extinction ratio in our parameter search and identify its mean systematic change across diverse cloud environments in both hemispheres. In regions outside the densest parts of the clouds, our reddening estimates are validated through comparisons with previous reddening maps. However, a notable discrepancy arises in comparison to other independent work based on XP spectra, which can be attributed to systematic offsets in their metallicity estimates. On the other hand, our metallicity scale exhibits reasonable agreement with the high-resolution spectroscopic abundance scale. We also assess the accuracy of the XP spectra by applying our calibrated models, and we confirm an increasing trend of flux overestimation at shorter wavelengths below 400 nm.

Keywords: Stellar abundances, Gaia, Milky Way Galaxy, Interstellar dust extinction
Development of a 90–600 MHz Meter-wave Solar Radio Spectrometer. Radio observation is important for understanding coronal mass ejections (CMEs), coronal shock waves, and high-energy electron acceleration. Here, we developed a new Chashan broadband solar radio spectrometer at a meter wavelength for observing the (super)fine structure of the solar radio burst spectrum. In the signal-receiving unit, we adopt an antenna system consisting of a 12 m large-aperture parabolic reflector and dual-line polarized logarithmic periodic feed source, as well as a high-precision Sun-tracking turntable system, all of which ensure the high-precision acquisition of solar radiation signals. For the digital receiver, we use a high-speed analog-to-digital converter with a sampling rate of 1.25 GSPS to directly sample the signal amplified and filtered by the analog receiver, simplifying the structure of the analog receiver, and design a 16k-point fast Fourier transform algorithm in the field programmable gate array to perform time–frequency transformation on the sampled signals. The default frequency and temporal resolution of the system are 76.294 kHz and 0.839 ms (up to 0.21 ms), respectively. The noise coefficient of the system is less than 1 dB, the dynamic range is more than 60 dB, and the sensitivity is as high as 1 sfu. We have observed a large number of radio bursts, including type I radio storms, hundreds of type III, ∼20 type II, and ∼15 type IV bursts in the past year. These high-quality data are useful in the further study of CMEs and associated particle acceleration and the origins of solar radio bursts.

Keywords: Solar radio telescopes, Flux calibration
A Deep Redshift Survey of the Perseus Cluster (A426): Spatial Distribution and Kinematics of Galaxies. We study the global kinematics of the Perseus galaxy cluster (A426) at redshift z = 0.017 using a large sample of galaxies from our new MMT/Hectospec spectroscopic observation for this cluster. The sample includes 1447 galaxies with measured redshifts within 60' from the cluster center (1148 from this MMT/Hectospec program and 299 from the literature). The resulting spectroscopic completeness is 67% at r-band apparent magnitude r Petro,0 ≤ 18.0 within 60' from the cluster center. To identify cluster member galaxies in this sample, we develop a new open-source Python package, CausticSNUpy. This code implements the algorithm of the caustic technique and yields 418 member galaxies within 60' of the cluster. We study the cluster using this sample of member galaxies. The cluster shows no significant signal of global rotation. A statistical test shows that the cluster does not have a noticeable substructure within 30'. We find two central regions where the X-ray-emitting intracluster medium and galaxies show significant velocity differences (&gt;7σ). On a large scale, however, the overall morphology and kinematics between the intracluster medium and galaxies agree well. Our results suggest that the Perseus cluster is a relaxed system and has not experienced a recent merger.

Keywords: Galaxy clusters, Perseus Cluster, Intracluster medium, Redshift surveys, Catalogs
β Cephei Pulsators in Eclipsing Binaries Observed with TESS. The combined strength of asteroseismology and empirical stellar basic parameter determinations for in-depth asteroseismic analysis of massive pulsators in eclipsing binaries shows great potential for treating the challenging and mysterious discrepancies between observations and models of stellar structure and the evolution of massive stars. This paper compiles a comprehensive list of massive pulsators in eclipsing binary systems observed with TESS. The TESS light curves and discrete Fourier transforms of a sample of 8055 stars of spectral type B0–B3 were examined for eclipses and stellar pulsations, and the ephemerides of the resulting subsample of massive pulsators in eclipsing binaries were computed. This subsample was also crossmatched with existing catalogs of massive pulsators. Until now, fewer than 30 β Cephei pulsators in eclipsing binaries have been reported in the literature. Here we announce a total of 78 pulsators of the β Cephei type in eclipsing binaries, 59 of which are new discoveries. Forty-three are recognized as definite, and 35 are candidate pulsators. Our sample of pulsating massive stars in eclipsing binaries allows for future asteroseismic modeling to better understand the internal mixing profile and to resolve the mass discrepancy in massive stars. We have already started follow-up work on some of the most interesting candidates.

Keywords: Observational astronomy, Period determination, Binary stars, Pulsating variable stars, Beta Cephei variable stars, Stellar pulsations, Massive stars, Multi-periodic pulsation, Space telescopes, Variable stars, Eclipsing binary stars, Asteroseismology