Sazuna/UAT_keywords huggingface dataset:
System Design of Medium-spectral-resolution Multi-object Fiber-fed Spectrograph for the Wide Field Multiplexed Survey Telescope (MUST). In recent years, the accelerated development of astronomy has created an urgent need for spectroscopic survey instruments with high speed and efficiency. The 6.5 m Wide Field Multiplexed Survey Telescope (MUST) proposed by Tsinghua University aims to address this need. In this paper, we present the medium spectral resolution multi-object fiber-fed spectrograph to meet the science requirement of the MUST project. The spectrograph, utilizing 92 mm × 92 mm large-size detectors, can accommodate 750 fibers with a core diameter of 150 μm. The transmissive camera features an 18° large field of view and F/1.4 fast focal ratio and achieves 90% average throughput for each channel. The system exhibits excellent image quality, enabling simultaneous acquisition of the spectra from 750 fibers across wide wavebands (365 nm ∼ 550 nm, 520 nm ∼ 765 nm, and 735 nm ∼ 980 nm) with the spectral resolution of 3000, 4000, and 5000. The system design strategies, trade-off study, and system design can serve as references for other spectroscopic survey instruments.

Keywords: Spectrometers, Astronomical instrumentation, Telescopes, Spectroscopy
Evaluating the Accuracy of Non-parametric Galaxy Morphological Indicator Measurements in the CSST Imaging Survey. The Chinese Space Station Telescope (CSST) is China's upcoming next-generation ultraviolet and optical survey telescope, with imaging resolution capabilities comparable to the Hubble Space Telescope (HST). In this study, we utilized a comprehensive sample of 3679 CSST realistic mock galaxies constructed from HST Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey/GOODS-North deep imaging observations, with stellar masses  logM*/M⊙&gt;9.0  and redshifts z &lt; 2. We evaluate the detection capabilities of CSST surveys and the accuracy in measuring the non-parametric morphological indicators (C, A, Gini, M20, AO, DO) of galaxies. Our findings show that in terms of galaxy detection capabilities, CSST's deep field surveys can achieve the same level as HST's deep field observations; however, in wide-field surveys, CSST exhibits a significant deficiency in detecting high-redshift, low-mass, low-surface-brightness galaxies. Regarding the measurement of galaxy morphology, CSST's deep field surveys achieve high accuracy across all indicators except for the asymmetry indicator (A), whereas its wide-field surveys suffer from significant systematic biases. We thus provide simple correction functions to adjust the non-parametric morphological indicators obtained from CSST's wide-field and deep-field observations, thereby aligning CSST measurements with those from HST. This adjustment enables the direct application of non-parametric morphological classification methods originally developed for HST data to galaxies observed by CSST.

Keywords: Surveys, Galaxy structure, Galaxies
Weak Lensing Analysis of A115, A2219 and A2261: Detection of Galaxy Groups and Filaments Around Clusters. We present a weak lensing and multi-wavelength analysis of three galaxy clusters: A115, A2219, and A2261. Weak lensing is performed using shape measurements made in short 60 s exposure images obtained using WIYN-ODI. Forced measurement is used to measure low Signal to Noise Ratio sources in individual exposures. We find the weak lensing significance map recovers the galaxy clusters and most galaxy groups in the wide 40 '  × 40 '  field. Significant parts of the filamentary structures over this field, as indicated by the galaxy number density map, were also successfully recovered in lensing significance maps. We find the amount of structure recovery depends on both the depth and average seeing of the images. In particular, we detect a &gt;9 Mpc long structure that contains the cluster A2219. We compare our weak lensing maps with Chandra, XMM, and LOFAR observations and find that A115 and A2219 show clear signs of ongoing mergers. In particular, we find a significant separation of hot ICM and the weak lensing contours in A115. On the other hand, while A2261 appears relaxed, based on radio and X-ray analysis, we find that it is likely interacting with a structure 700 kpc SW of the main cluster. We also successfully recovered mass structures in two regions around A2261 indicated by diffuse X-ray emission in XMM images.

Keywords: Galaxy clusters, Radio sources, X-ray astronomy, Weak gravitational lensing
Redshifts of Objects near 3C 220.3. In the course of studying the 3C 220.3 lensing system, spectra were obtained with the Binospec instrument on the MMT for 511 additional objects in 3C 220.3's vicinity. These gave 146 good-quality galaxy redshifts and identified 126 Galactic stars. The galaxy redshift histogram shows a peak near 3C 220.3's redshift, but there is no evidence for or against a galaxy group within 2 Mpc of 3C 220.3 itself. The spectra revealed 12 active galactic nuclei candidates, including a likely z ≍ 4.64 broad-line QSO. Visible and near-infrared imaging with HST allowed morphological classifications of 14 galaxies. One system is a potential analog of the Milky Way─Large Magellanic Cloud system with stellar mass ratio ∼0.6.

Keywords: Surveys, Celestial objects catalogs, Redshift surveys, Catalogs
A Hydrodynamical Thermal Irradiated Wind from the Outer Thin Accretion Disk in Low-luminosity Active Galactic Nuclei. Evidently, low-luminosity active galactic nuclei (LLAGNs) are comprised of an inner advective disk and an outer geometrically thin disk. Wind is inevitable in LLAGNs, mainly interpreted in an indirect way; also, the evidence is growing for the presence of wind in the outer thin disk. We present a hydrodynamics (HD) model for wind from the outer thin disk, where the main driver is the inner disk irradiation (which is parameterized by a number x in hydrostatic equilibrium equation) and the heating mechanism is photoionization. The model works for low-intensity irradiation or from a height zs in the optically thin medium. We solve the model equations in cylindrical coordinates along the z-axis for a given radius r assuming a tiny vertical speed vz (≪cs sound speed). The sonic point conditions assure an isobaric regime above the sonic height ( zmax ); in addition to the height  zf(≪zmax ), the radial pressure gradient also supports the fluid rotation, and both jointly assure a wind ejection from the  zmax  with fluid speed. The  zmax  increases with x, and beyond a large  zmax  (say  ztmax  corresponding to maximum x), there is no physical solution. We start the computation from the outer radius  rothin  to the inner  rinthin  with a Bondi mass accretion rate  ṀBondi  to explore the r dependency of the mass inflow rate  Ṁ  and wind properties. We constrain the model by fixing  Ṁ  at  rinthin  from the observations of NGC 1097 and check the feasibility of the model by comparing the energetics with the observed bolometric luminosity. The wind is equatorial with a viewing angle i &gt; 85° and capable of generating red/blueshifted lines, which would be a general characteristics for LLAGNs.

Keywords: Accretion, Hydrodynamics, Stellar winds, Low-luminosity active galactic nuclei, Stellar accretion
Improved Fermi Blazar Candidate Classifications with SRG/eROSITA X-Ray Counterparts Using Machine Learning. Gamma-ray sources are among the highest energy phenomena in the Universe and are important laboratories for the study of particle acceleration and relativistic astrophysics. The classification of gamma-ray sources in the past has been aided by the incorporation of multiwavelength observations. In this study, we classify different types of active galactic nuclei by applying machine learning (ML) techniques to a crossmatch of newly released gamma-ray and X-ray catalogs for the first time: the Fermi Gamma-ray Large Area Telescope Fourth Source Catalog and the recent, first release of the SRG/eROSITA All-Sky X-ray Survey. We investigate the effects that different features from this dataset have on the classification accuracy and compare the ML model to traditional methods that use a simple cut in parameter space. We find that a variant of the Gradient Boosting ML model leads to an increased classification accuracy of previously manually classified sources (99.2%) compared to that of traditional methods (92.0%). Our models, trained on gamma-ray and X-ray data, even outperform recent ML models trained on gamma-ray data alone, which achieve accuracies no greater than 92.4%. We also find that the addition of X-ray data to gamma ray data increases both the accuracy and the number of sources classified with high confidence. Finally, we apply our model to blazar candidates of unknown type within the dataset and find 221 sources with a &gt;90% probability of being either a BL Lacertae object or flat spectrum radio quasar. We consider all classifications to be candidates since the labels are derived from the Fermi catalog itself, not optical spectroscopic surveys. With the increasing number of gamma-ray and X-ray detections and large numbers of sources yet to be classified, this work highlights the strong potential of ML in the classification of multi-wavelength astronomical datasets.

Keywords: BL Lacertae objects, Classification, Gamma-ray sources, Blazars, Flat-spectrum radio quasars, X-ray sources
The Photometric, Spectroscopic and Orbital Period Investigations of Ten Short Period Contact Binaries. In this paper, photometric and spectroscopic data from ten contact binaries (CBs) are presented and analyzed. We found that CzeV710 was a totally eclipsing binary with a very low mass ratio (q ∼ 0.14), V401 Cam was a W-subtype totally eclipsing binary (f = 35.5%), the others were shallow CBs. Using O ‑ C, we further discovered that five of them exhibit secular period changes, one show linear variations, and four show cyclic variations. For V1030 Cas, a long-term decrease superposed a cyclic variation was discovered. Except CzeV710, the light curves for the other nine targets show the O'Connell effect, and a cool star-spot on the active component can lead to a good fit of the asymmetric light curves. In addition, based on the Large Sky Area Multi-Object Fiber Spectroscopic Telescope low-resolution spectroscopic measurements, the equivalent width of the Hα emission line is used as a tracer of chromospheric activity. The analysis of the Hα emission line and the O'Connell effect suggested that our targets are active at present. After calculating the instability parameters, we also found that these ten targets are relatively stable now. By comparing the parameters of 360 short-period eclipsing binaries, we found that CBs have a minimum orbital angular momentum in close binaries, which indicates that they are at the end of the evolution chain of binaries. The evolution of CBs is very complex; the third body and angular momentum loss can help shallow CBs evolve into medium- and deep-ones.

Keywords: Eclipsing binary stars, Spectroscopic binary stars, Stellar activity
Analysis of Newly Cataloged Open Star Cluster UPK 220 with Gaia DR3 and TESS: Discovering Member Variable Stars. Studies on star clusters with the same age and initial chemical composition have gained momentum in recent years with the use of Gaia. In addition, the discovery of new clusters with Gaia has increased the number of open clusters (OCs) to be examined. Many of these discovered sources are intermediate-age OCs and have not been analyzed in detail yet. In this study, we focused on newly cataloged OC UPK 220. The fundamental parameters (distance, age, metallicity and reddening) of UPK 220 were determined by analysing the variable stars within the cluster, while simultaneously constraining the parameters of the variable stars using these cluster parameters. To achieve this, we combined GaiaDR3 and TESS photometric observations. Using GaiaDR3, we derive fundamental parameters of UPK 220 through membership analyses, and with TESS, we discovered eight member variable stars. We also extracted the atmospheric parameters (log g, [Fe/H] and Teff) for the variable stars using SED, GSP-Phot and GSP-Spec, and MESA models.

Keywords: Stellar photometry, Open star clusters, Variable stars, Stellar evolution
Polytropic Wind-driven Bubbles and their Shock Structures in Radially Stratified Ambient Media. We extend the analytic expressions for polytropic wind-driven bubbles and their shock structures, formulated initially in Koo &amp; McKee, focusing on spherically symmetric configurations in astrophysical environments with ρ ∝ r‑2, which arises naturally in the star-forming environment and has applications to winds flowing into a preexisting bubble. Wind luminosity is assumed to be constant, and as a result, the shock velocities of these bubbles are constant in time. The ratio of specific heats is assumed to be the same in the shocked ambient medium and the shocked wind. Numerical results are presented for one selected ratio of wind density to ambient density. Exact ODEs are written for the compressed wind region, and approximate solutions are found by fitting the ODE solutions. By analyzing the interactions between stellar winds and ambient media in the strong compression limit, we model the formation and evolution of spherical bubbles, highlighting their shock fronts and contact discontinuities. Our analytic method provides an intuitive approach to calculating the thickness of bubble shells, which is crucial for understanding their dynamics and observational characteristics. A numerical method explores conditions without explicitly requiring the strong compression limit, and then we compare numerical to analytical results under various conditions.

Keywords: Stellar-interstellar interactions, Stellar wind bubbles, Supernova remnants, Stellar winds, Shocks, Interstellar medium wind
Systematic Search for FFPs in KMTNet Full-frame Images. I. Photometry Pipeline. To exhume the buried signatures of free-floating planets (FFPs) with small angular Einstein radius θE, we build a new full-frame difference image pipeline for the Korean Microlensing Telescope Network (KMTNet) survey based on the newly optimized pySIS package. We introduce the detailed processes of the new pipeline, including frame registration, difference image analysis, and light curve extraction. To test this pipeline, we extract one-year light curves for 483,068 stars with I ≲ 17 and conduct a model-independent search for microlensing events. The search finds 36 microlensing events, including five new events and six events discovered by other collaborations but missed by previous KMTNet searches. We find that the light curves from the new pipeline are precise enough to be sensitive to FFPs with θE ∼ 1 μas. Using the new pipeline, a complete FFP search on the eight-year KMTNet images can be finished within six months and then yield the FFP mass function. The new pipeline can be used for a new KMTNet AlertFinder system, with significantly reduced false positives.

Keywords: Light curves, Free floating planets, Gravitational microlensing exoplanet detection, Photometry
Architecture of the Tianyu Software: Relative Photometry as a Case Study. The Tianyu telescope, a 1 m robotic optical survey instrument to be constructed in Lenghu, Qinghai, China, is designed for detecting transiting exoplanets, variable stars, and transients. It requires highly automated, optimally distributed, easily extendable, and highly flexible software to enable the data processing for the raw data at rates exceeding 500 MB s–1. In this work, we introduce the architecture of the Tianyu pipeline and use relative photometry as a case to demonstrate its high scalability and efficiency. This pipeline is tested on the data collected from Muguang Observatory and Xinglong Observatory. The pipeline demonstrates high scalability, with most processing stages increasing in throughput as the number of consumers grows. Compared to a single consumer, the median throughput of image calibration, alignment, and flux extraction increases by 41%, 257%, and 107%, respectively, when using five consumers, while image stacking exhibits limited scalability due to I/O constraints. In our tests, the pipeline was able to detect two transiting sources. Besides, the pipeline captures variability in the light curves of nine known and two previously unknown variable sources in the testing data. Meanwhile, the differential photometric precision of the light curves is near the theoretical limitation. These results indicate that this pipeline is suitable for detecting transiting exoplanets and variable stars. This work builds the foundation for further development of the Tianyu software.7 7The code of this work is available at https://github.com/ruiyicheng/Tianyu_pipeline. The code of this work is available at https://github.com/ruiyicheng/Tianyu_pipeline.

Keywords: Photometry, Astronomy software
Multipole Analysis and Application to Supernova Remnant X-Ray Images. We develop a multipole analysis method for images with a circular boundary, then apply it to supernova remnant (SNR) images. The morphology of SNR images is related to several factors, including the inhomogeneities of the supernova ejecta and of the circumstellar medium in which the ejecta and shock wave travel. The current multipole method corrects some errors in a previously presented method, and applies the new analysis to test for differences in X-ray image morphology between Type Ia and core-collapse type SNRs. We find there is no clear difference between the two SNR types in morphology as measured by multipole moments.

Keywords: Supernova remnants, Astronomical techniques, Astronomy data analysis, Astronomical methods
The Impact of Fiber Cross Contamination on Radial Velocity Precision. High-resolution spectrographs with precise radial velocity (PRV) capabilities require careful considerations in instrumental design and data processing in order to reach the 10 cm s‑1-level precision, which is needed for detecting Earth-like planets. In this work, we investigate the impact of fiber cross contamination on the RV precision via simulations, as modern PRV spectrographs often have multiple fiber traces on their spectral images. We simulated extracted 1D spectra under the preliminary design of CHORUS, short for the Canary Hybrid Optical high-Resolution Ultra-stable Spectrograph, a dual-arm PRV spectrograph under construction for the Gran Telescopio de Canarias. We considered two types of fiber cross contaminations: contamination from calibration traces to neighboring science traces (or cal-sci contamination) and between science traces (or sci–sci contamination). We present results in four different scenarios: photon noise only, cal-sci contamination only, sci–sci contamination only, and all effects combined. For the preliminary design of CHORUS, we estimated that the cal-sci contamination fraction is smaller than 0.0001% in flux across the whole CCD for either arm, resulting in a negligible impact on the RV precision. Assuming worst-case scenarios, we estimated the sci–sci contamination to be up to 0.1% in some traces, corresponding to an additional RV error of up to 10 cm s‑1. We demonstrate the importance of considering fiber-trace spacing and cross contamination in PRV spectrographs, and we recommend careful design, operation, and spectral extraction algorithms to minimize and mitigate cross contamination to achieve the best possible instrumental RV precision.

Keywords: Radial velocity, Spectrometers, Astronomical instrumentation, Spectroscopy
Searching for Strong Lenses from DESI Legacy Surveys with a Hybrid CNN-Transformer Architecture with Self-supervised Learning. Strong gravitational lensing is a valuable tool for studying the mass distributions and structural evolution of galaxies over cosmic time. However, the rarity and complexity of strong lenses necessitate the development of automatic and efficient methods for identifying them within enormous data sets. Therefore, we propose a novel deep learning model, MCT-Lens (MoCo-CNN-Transformer Lens Classifier), which incorporates a Momentum Contrast (MoCo) self-supervised learning module for the pretraining phase and a Convolutional Neural Network (CNN)-Transformer hybrid architecture for the classification phase. In the pretraining phase, we utilize the MoCo self-supervised learning module to extract generalizable features from 3.5 million unlabeled images from the Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys, while in the classification phase, our hybrid CNN-Transformer-based classifier will identify strong lenses using the feature vectors provided above, which combines the advantages of CNNs in local feature extraction and Transformers in global information modeling for given galaxy images. We evaluate MCT-Lens' performance with the testing data sets based on the NeuraLens database (https://sites.google.com/usfca.edu/neuralens). The results demonstrate that MCT-Lens achieves a precision improvement of 7% and a recall improvement of 3% compared to the existing baseline models proposed by Jacobs et al. and Huang et al. We then applied MCT-Lens to the data set (https://github.com/georgestein/ssl-legacysurvey) pulled from the DESI Legacy Survey Data Release 9 given by Stein et al. and identified 56 new high-quality strong lens candidates, which are not included in the catalogs published by Huang et al. and Stein et al., offering additional sources for seeking and confirming strong lensing systems with DESI spectra in the future. The data and programs used in this paper are publicly accessible online (https://github.com/yjr530/MCT-Lens).

Keywords: Strong gravitational lensing, Convolutional neural networks
Cryoscope: A Cryogenic Infrared Survey Telescope in Antarctica. We present Cryoscope, a new 50 deg2 field-of-view, 1.2 m aperture, Kdark survey telescope to be located at Dome C, Antarctica. Cryoscope has an innovative optical–thermal design wherein the entire telescope is cryogenically cooled. Cryoscope also explores new detector technology to cost-effectively tile the full focal plane. Leveraging the dark Antarctic sky and minimizing telescope thermal emission, Cryoscope achieves unprecedented deep, wide, fast, and red observations, matching and exceeding volumetric survey speeds from the Ultraviolet Explorer, Vera Rubin Observatory, Nancy Grace Roman Space Telescope, SPHEREx, and NEO Surveyor. By providing coverage beyond wavelengths of 2 μm, we aim to create the most comprehensive dynamic movie of the most obscured reaches of the Universe. Cryoscope will be a dedicated discovery engine for electromagnetic emission from coalescing compact binaries, Earth-like exoplanets orbiting cold stars, and multiple facets of time-domain, stellar, and solar system science. In this paper, we describe the scientific drivers and technical innovations for this new discovery engine operating in the Kdark passband, why we choose to deploy it in Antarctica, and the status of a fifth-scale prototype designed as a Pathfinder to retire technological risks prior to full-scale implementation. We plan to deploy the Cryoscope Pathfinder to Dome C in 2026 December and the full-scale telescope by 2030.

Keywords: Exoplanets, Stellar mergers, Surveys, Infrared astronomy, Gravitational wave astronomy, Astronomical detectors, Astronomical instrumentation, Time domain astronomy, Variable stars, Solar system astronomy