Sazuna/UAT_keywords huggingface dataset:
VLTI/GRAVITY Observations of AF Lep b: Preference for Circular Orbits, Cloudy Atmospheres, and a Moderately Enhanced Metallicity. Direct imaging observations are biased toward wide-separation, massive companions that have degenerate formation histories. Although the majority of exoplanets are expected to form via core accretion, most directly imaged exoplanets have not been convincingly demonstrated to follow this formation pathway. We obtained new interferometric observations of the directly imaged giant planet AF Lep b with the VLTI/GRAVITY instrument. We present three epochs of ∼50 μas relative astrometry and the K-band spectrum of the planet for the first time at a resolution of R = 500. Using only these measurements, spanning less than 2 months, and the Hipparcos-Gaia Catalogue of Accelerations, we are able to significantly constrain the planet's orbit; this bodes well for interferometric observations of planets discovered by Gaia DR4. Including all available measurements of the planet, we infer an effectively circular orbit (e &lt; 0.02, 0.07, and 0.13 at 1σ, 2σ, and 3σ, respectively) in spin─orbit alignment with the host and measure a dynamical mass of M  p  = 3.75M Jup ± 0.5M Jup. Models of the spectrum of the planet show that it is metal-rich ([M/H] = 0.75 ± 0.25), with a C/O abundance encompassing the solar value. This ensemble of results shows that the planet is consistent with core accretion formation.

Keywords: Optical interferometry, Direct imaging, Orbit determination, Extrasolar gaseous giant planets, Exoplanet atmospheres
Real-time Pulse Search and Positioning Method for Baseband Data Based on Matched Filtering. Fast radio bursts (FRBs) are the most intense radio explosions known, yet their origins remain a significant astrophysical mystery. High-time-resolution pulse searching has opened new avenues for studying narrow and faint pulses, promising substantial improvements in pulse detection efficiency and accuracy and potentially leading to significant scientific discoveries. However, the increase in time resolution results in exponential data volume growth, presenting considerable challenges for data processing. The real-time processing of vast amounts of data and the rapid detection of FRB pulse signals have become bottlenecks in high-time-resolution pulse search research. To address these challenges, we propose a real-time pulse search and positioning method for baseband data based on matched filtering. This method performs preliminary pulse searching and positioning within the baseband data, enabling the selection of effective data segments for subsequent dedispersion and analysis, thereby significantly reducing the data-processing burden. Compared to traditional coherent dedispersion methods, our approach exhibits superior performance in both pulse detection efficiency and dispersion tolerance. Utilizing GPU parallel acceleration, the method can process baseband data streams with 1 ns time resolution in real time, facilitating the detection of narrower and fainter pulse signals. Analysis of 1 ns time-resolution baseband data from FRB 121102 not only successfully identifies all known pulses, but also reveals three new pulses, demonstrating the feasibility and effectiveness of our method.

Keywords: Radio astronomy, High time resolution astrophysics
A Comprehensive Analysis of Spitzer 4.5 μm Phase Curves of Hot Jupiters. Although exoplanetary science was not initially projected to be a substantial part of the Spitzer mission, its exoplanet observations set the stage for current and future surveys with JWST and Ariel. We present a comprehensive reduction and analysis of Spitzer's 4.5 μm phase curves of 29 hot Jupiters on low-eccentricity orbits. The analysis, performed with the Spitzer Phase Curve Analysis pipeline, confirms that BLISS mapping is the best detrending scheme of the three independent schemes we tested for most, but not all, observations. Visual inspection remains necessary to ensure consistency across detrending methods due to the diversity of phase-curve data and systematics. Regardless of the model selection scheme, whether using the lowest BIC or a uniform detrending approach, we observe the same trends, or lack thereof. We explore phase-curve trends as a function of irradiation temperature, orbital period, planetary radius, mass, and stellar effective temperature. We discuss the trends that are robustly detected and provide potential explanations for those that are not observed. While it is almost tautological that planets receiving greater instellation are hotter, we are still far from confirming dynamical theories of heat transport in hot Jupiter atmospheres due to the sample's diversity. Even among planets with similar temperatures, other factors like rotation and metallicity vary significantly. Larger, curated sample sizes and higher-fidelity phase-curve measurements from JWST and Ariel are needed to firmly establish the parameters governing day–night heat transport on synchronously rotating planets.

Keywords: Exoplanet astronomy, Exoplanet atmospheric dynamics, Exoplanet atmospheres
Precise Orbit Determination of Mars-crossing Asteroids. This study investigates the orbit determination of the Mars-crossing asteroids (MCAs) with a focus on the possibility of detecting their Yarkovsky signals. We analyze the influences of force model uncertainties on MCA orbits, including the uncertainty of the main asteroid belt, and the uncertainty of the major planets' ephemeris. The main asteroid belt is modeled using 343 asteroids and a ring structure. The Yarkovsky effect's quadratic nature allows it to dominate over extended observation periods. To address dynamical errors and potential interactions with the main asteroid belt, we employ not only a traditional seven-dimensional differential corrector but also a nine-dimensional differential corrector that considers radial, vertical, and transversal forces. Comparison shows that the latter approach enhances the fit to observational data. However, the reliability of the Yarkovsky parameter is not enhanced because the estimation of the radial component is physically unacceptable. Despite incorporating precise Gaia data, our analysis does not conclusively detect a Yarkovsky effect on MCAs due to uncertainties in the force model. Nevertheless, our research advances our understanding of MCA dynamics, identifying five potential candidates whose Yarkovsky effect may be observable.

Keywords: Astrometry, Orbit determination
Simulating Gravitational Microlensing Events by TESS: Predictions on Statistics and Properties. We study the statistics and properties of microlensing events that can be detected by the Transiting Exoplanet Survey Satellite (TESS) based on Monte Carlo simulations. We simulate potential microlensing events from a sample of TESS Candidate Target List (CTL) stars by assuming different observational time spans (or different numbers of sectors for each star) and a wide range of lens masses, i.e., M l ∈ [0.1 M ⊕, 2 M ⊙]. On average, the microlensing optical depth and the event rate for CTL stars are ≃0.2 × 10‑9 and ΓTESS ≃ 0.6 × 10‑9 star–1 day–1, respectively. The microlensing optical depth decreases with increasing CTL priority, whereas the efficiency for detecting their microlensing signals enhances with priority. Additionally, we simulate microlensing events from TESS Full Frame Image (FFI) stars extracted from the TESS-SPOC pipeline. The optical depth and event rate for these stars are on average ≃1–3 × 10‑9, and ΓTESS ≃ 1–4 × 10‑9 star–1 day–1, and their highest values occur for Sector 12. The total number of microlensing events for the CTL stars is N e,tot ∼ 0.03, whereas for the FFI stars the number of events per star during the 27.4 day observing windows is  . Based on four criteria we extract the detectable microlensing events and evaluate the detection efficiencies. The highest efficiency for detecting microlensing events from the TESS data occurs for lens masses of  , ‑2.5], i.e., super-Earths to Jupiter-mass free floating planets. The detectable microlensing events from the TESS stars are significantly affected by both finite-source and parallax effects.

Keywords: Space vehicle instruments, Gravitational microlensing exoplanet detection, Monte Carlo methods, Space telescopes, Gravitational microlensing, Exoplanet detection methods, Astronomical simulations
Three Years of High-contrast Imaging of the PDS 70 b and c Exoplanets at Hα with MagAO-X: Evidence of Strong Protoplanet Hα Variability and Circumplanetary Dust. We present 3 yr of high-contrast imaging of the PDS 70 b and c accreting protoplanets with the new extreme AO system MagAO-X as part of the MaxProtoPlanetS survey of Hα protoplanets. In 2023 and 2024, our sharp (25─27 mas FWHM), well-AO-corrected (20%─26% Strehl), deep (2─3.6 hr) images detected compact (r ∼ 30 mas; r ∼ 3 au) circumplanetary disks (CPDs) surrounding both protoplanets. Starlight scattering off the front edge of these dusty CPDs is the likely source of the bright compact continuum light detected within ∼30 mas of both planets in our simultaneously obtained continuum 668 nm filter images. After subtraction of contaminating continuum and point-spread function residuals with pyKLIP angular differential imaging and spectral differential imaging, we obtained high-contrast ASDI Hα images of both planets in 2022, 2023, and 2024. We find the Hα line flux of planet b fell by (8.1 ± 1.6) × 10−16 erg s−1 cm−2, a factor of 4.6 drop in flux from 2022 to 2023. In 2024 March, planet b continued to be faint with just a slight 1.6× rise to an Hα line flux of (3.64 ± 0.87) × 10−16 erg s−1 cm−2. For c, we measure a significant increase of (2.74 ± 0.51) × 10−16 erg s−1 cm−2 from 2023 to 2024, which is a factor of 2.3 increase. So both protoplanets have recently experienced significant Hα variability with ∼1 yr sampling. In 2024, planet c is brighter than b: as c is brightening and b generally fading. We also tentatively detect one new point source "CC3" inside the inner disk (∼49 mas; at PA ∼ 295°; 2024) with orbital motion roughly consistent with a ∼5.6 au orbit.

Keywords: High contrast techniques, Accretion, Exoplanet atmospheric variability, Astronomical optics, Adaptive optics, Exoplanet astronomy, Coronagraphic imaging, Direct imaging, Exoplanet detection methods, Exoplanet formation
Astrometric Calibration of MagAO-X with Updated Solutions for HD 165054 Field Stars. MagAO-X is a recently commissioned extreme adaptive optics instrument for the Magellan Clay 6.5 m telescope at Las Campanas Observatory in Chile. MagAO-X had first light in 2019 and subsequent commissioning observations in 2022 and 2023. An essential step for the commissioning of any new instrument is the calibration of the conversion of detector coordinates to angular sky coordinates, which we accomplish with observations of HD 165054. The background stars adjacent to HD 165054 in Baade's Window are in a fortuitous configuration for the astrometric calibration of natural-guide-star high-contrast imaging instruments. We extend past work to connect these stars' positions to absolute astrometry for HD 165054 itself using Gaia Data Release 3 data, and bootstrap the creation of an astrometric solution for our new high-contrast imaging instrument. Through Markov Chain Monte Carlo analysis of the historical data and position measurements from MagAO-X, we obtain updated astrometric parameters for the seven background stars and an astrometric calibration of the MagAO-X science cameras.

Keywords: Astronomical optics, Adaptive optics, Astronomical techniques, Astrometry, Exoplanet detection methods
The Subparsec-scale Structure and Evolution of Centaurus A. III. A Multi-epoch Spectral and Polarimetric VLBA Study. The Centaurus A radio galaxy, due to its proximity, presents itself as one of the few systems that allow the study of relativistic jet outflows at subparsec distances from the central supermassive black holes, with high signal to noise. We present the results from the first multi-epoch spectropolarimetric observations of Centaurus A at milliarcsecond resolution, with a continuous frequency coverage of 4.59‑7.78 GHz. Using a Bayesian framework, we perform a comprehensive study of the jet kinematics, and discuss aspects of the jet geometry, including the jet inclination angle, jet opening angle, and the jet expansion profile. We calculate an upper limit on the jet's inclination to the line of sight to be &lt;25°, implying the lower limit on the intrinsic jet speed to be 0.2c. On the observed very long baseline array scales, we detect new jet components launched by the central engine since our previous study. Using the observed frequency-dependent core shift in Centaurus A, we find the jet to have reached constant bulk speed and conical outflow at the regions probed by the base of the jet at 7.78‑4.59 GHz, and we also estimate the location of the central black hole further upstream. Through polarimetric analysis (by applying rotation measure synthesis for the first time on very long baseline interferometry data), we find evidence to suggest the possible onset of acceleration toward the leading edge of Centaurus A's subparsec-scale jet studied here.

Keywords: Very long baseline interferometry, Relativistic jets, Active galactic nuclei, Interferometers
Retrievals on NIRCam Transmission and Emission Spectra of HD 189733b with PLATON 6, a GPU Code for the JWST Era. We present the 2.4─5.0 μm JWST/NIRCam emission spectrum of HD 189733b, along with an independent re-reduction of the previously published transmission spectrum at the same wavelengths. We use an upgraded version of PLanetary Atmospheric Tool for Observer Noobs (PLATON) to retrieve atmospheric parameters from both geometries. In transit, we obtain [M/H] =   and C/O =  , assuming a power-law haze and equilibrium chemistry with methane depletion. In eclipse, we obtain [M/H] =   and C/O =  , assuming a clear atmosphere and equilibrium chemistry without methane depletion. These results are consistent with each other, and with a rerun of our previously published joint retrieval of Hubble Space Telescope and Spitzer transmission and emission spectra. Accounting for methane depletion decreases the C/O ratio by 0.14/0.04 (transmission/emission), but changing the limb cloud parameterization does not affect the C/O ratio by more than 0.06. We detect H2O, CO2, CO, and H2S in both the NIRCam transmission and emission spectra, find that methane is depleted on the terminator, and confirm with VULCAN that photochemistry is a potential cause of this depletion. We also find tentative (1.8σ) evidence of a dayside thermal inversion at millibar pressures. Finally, we take this opportunity to introduce a new version of PLATON. PLATON 6 supports GPU computation, speeding up the code up to 10×. It also supports free retrievals using both volume mixing ratio and centered-log ratio priors; emission from planetary surfaces of different compositions; updated opacities at improved resolution; and Pareto smoothed importance sampling leave-one-out cross-validation.

Keywords: Exoplanet atmospheric composition , James Webb Space Telescope, Exoplanet atmospheres
frb-voe: A Real-time Virtual Observatory Event Alert Service for Fast Radio Bursts. We present frb-voe, a publicly available software package that enables radio observatories to broadcast fast radio burst (FRB) alerts to subscribers through low-latency virtual observatory events (VOEvents). We describe a use case of frb-voe by the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) Collaboration, which has broadcast thousands of FRB alerts to subscribers worldwide. Using this service, observers have daily opportunities to conduct rapid multiwavelength follow-up observations of new FRB sources. Alerts are distributed as machine-readable reports and as emails containing FRB metadata, and are available to the public within approximately 13 s of detection. A sortable database and a downloadable JSON file containing FRB metadata from all broadcast alerts can be found on CHIME/FRB's public webpage. The frb-voe service also provides users with the ability to retrieve FRB names from the Transient Name Server through the frb-voe client user interface. The frb-voe service can act as a foundation on which any observatory that detects FRBs can build its own VOEvent broadcasting service to contribute to the coordinated multiwavelength follow-up of astrophysical transients.

Keywords: Astronomy software, Radio transient sources
Faint White Dwarf Flux Standards: Data and Models. Fainter standard stars are essential for the calibration of larger telescopes. This work adds to the calibration spectra (CALSPEC) database of 19 faint white dwarfs (WDs) with all-sky coverage and V magnitudes between 16.5 and 18.7. Included for these stars is a new ultraviolet (UV) Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph between 1150 and 3000 Å with a resolution of ∼500. Pure hydrogen WD models are fit to these UV spectra and to six-band HST/Wide Field Camera 3 photometry at 0.28–1.6 μm to construct predicted model spectral energy distributions covering wavelengths from 900 Å to the James Webb Space Telescope limit of 30 μm using well-established CALSPEC procedures for producing flux standards with the goal of 1% accuracy.

Keywords: DA stars
The Solar Neighborhood. LII. M Dwarf Twin Binaries—Presumed Identical Twins Appear Fraternal in Variability, Rotation, Hα, and X-Rays. We present an investigation into the rotation and stellar activity of four fully convective M dwarf "twin" wide binaries. Components in each pair have (1) astrometry confirming they are common-proper-motion binaries, (2) Gaia BP, RP, and 2MASS J, H, and K  s  magnitudes matching within 0.10 mag, and (3) presumably the same age and composition. We report long-term photometry, rotation periods, multiepoch Hα equivalent widths, X-ray luminosities, time series radial velocities, and speckle observations for all components. Although it might be expected for the twin components to have matching magnetic attributes, this is not the case. Decade-long photometry of GJ 1183 AB indicates consistently higher spot activity on A than B, a trend matched by A appearing 58% ± 9% stronger in L X and 26% ± 9% stronger in Hα on average—this is despite similar rotation periods of A = 0.86 day and B = 0.68 day, thereby informing the range in activity for otherwise identical and similarly rotating M dwarfs. The young β Pic Moving Group member 2MA 0201+0117 AB displays a consistently more active B component that is 3.6 ± 0.5 times stronger in L X and 52% ± 19% stronger in Hα on average, with distinct rotation at A = 6.01 days and B = 3.30 days. Finally, NLTT 44989 AB displays remarkable differences with implications for spindown evolution—B has sustained Hα emission while A shows absorption, and B is ≥39 ± 4 times stronger in L X, presumably stemming from the surprisingly different rotation periods of A = 38 days and B = 6.55 days. The last system, KX Com, has an unresolved radial velocity companion, and is therefore not a twin system.

Keywords: M dwarf stars, Stellar activity, Magnetic variable stars, Wide binary stars, Stellar rotation, X-ray stars, Stellar evolution
Identifying Telescope Usage in Astrophysics Publications: A Machine Learning Framework for Institutional Research Management at Observatories. Large scientific institutions, such as the Space Telescope Science Institute, track the usage of their facilities to understand the needs of the research community. Astrophysicists incorporate facility usage data into their scientific publications, embedding this information in plain text. Traditional automatic search queries prove unreliable for accurate tracking due to the misidentification of facility names in plain text. As automatic search queries fail, researchers are required to manually classify publications for facility usage, which consumes valuable research time. In this work, we introduce a machine learning classification framework for the automatic identification of facility usage of observation sections in astrophysics publications. Our framework identifies sentences containing telescope mission keywords (e.g., Kepler and TESS) in each publication. Subsequently, the identified sentences are transformed using term frequency–inverse document frequency and classified with a support vector machine. The classification framework leverages the context surrounding the identified telescope mission keywords to provide relevant information to the classifier. The framework successfully classifies the usage of MAST-hosted missions with a 92.9% accuracy. Furthermore, our framework demonstrates robustness when compared to other approaches, considering common metrics and computational complexity. The framework's interpretability makes it adaptable for use across observatories and other scientific facilities worldwide.

Keywords: Random Forests, Open source software, Support vector machine, Classification
Reinforcement Learning for Data-driven Workflows in Radio Interferometry. I. Principal Demonstration in Calibration. Radio interferometry is an observational technique used to study astrophysical phenomena. Data gathered by an interferometer require substantial processing before astronomers can extract scientific information from them. Data processing consists of a sequence of calibration and analysis procedures where choices must be made about the sequence of procedures as well as the specific configuration of the procedure itself. These choices are typically based on a combination of measurable data characteristics, an understanding of the instrument itself, an appreciation of the trade-offs between compute cost and accuracy, and a learned understanding of what is considered best practice. A metric of absolute correctness is not always available and validity is often subject to human judgment. The underlying principles and software configurations to discern a reasonable workflow for a given data set is the subject of training workshops for students and scientists. Our goal is to use objective metrics that quantify best practice, and numerically map out the decision space with respect to our metrics. With these objective metrics we demonstrate an automated, data-driven, decision system that is capable of sequencing the optimal action(s) for processing interferometric data. This paper introduces a simplified description of the principles behind interferometry and the procedures required for data processing. We highlight the issues with current automation approaches and propose our ideas for solving these bottlenecks. A prototype is demonstrated and the results are discussed.

Keywords: Interdisciplinary astronomy, Computational methods, Computational astronomy, Radio astronomy