Sazuna/UAT_keywords huggingface dataset:
Physical Properties of Embedded Clusters in ATLASGAL Clumps with H II Regions. Using the optimal sampling model, we synthesized the embedded clusters of ATLASGAL clumps with H II regions (H II-clumps). The 0.1 Myr isochrone was used to estimate the bolometric luminosity of each star in an embedded cluster, we also added the accretion luminosity of each star in the embedded cluster. The total bolometric luminosity of synthetic embedded clusters can well fit the observed bolometric luminosity of H II-clumps. More realistically, we considered the age spread in the young star and protostar populations in embedded clusters of H II-clumps by modeling both constant and time-varying star formation histories (SFHs). According to the age distribution of the stellar population, we distributed the appropriate isochrones to each star, and sorted out the fraction of stellar objects that are still protostars (Class 0 and Class I phases) to properly add their accretion luminosities. Compared to a constant SFH, burst-like and time-dependent SFHs can better fit the observational data. We found that as long as 20% of the stars within the embedded cluster are still accreting, the contribution of accretion luminosity will be significant to the total bolometric luminosity of low-mass H II-clumps with mass log10(M cl/M ⊙) &lt; 2.8. Variations in the accretion rate, the SFE and the initial mass function and more physical processes like the external heating from H II regions and the flaring from pre-main sequence stars and protostars need to be investigated to further explain the excess luminosity of low-mass H II-clumps.

Keywords: Molecular gas, Compact H II region, Initial mass function, Protoclusters, Dust continuum emission, Protostars
The Star Formation Histories, Star Formation Efficiencies and Ionizing Sources of ATLASGAL Clumps with H II Regions. 1226 ATLASGAL clumps with H II regions (H II-clumps) were matched with radio sources in the CORNISH-North/South surveys, and 392 of them have corresponding radio sources. We determined the stellar luminosity L *,T84 according to the Lyman continuum flux N Ly. When the bolometric luminosity of H II-clumps is less than log10(L bol,obs/L ⊙) ≍3.7, corresponding to a clump mass log10(M cl/M ⊙) ≍ 2.55, the values of L *,T84 derived from N Ly overestimate the actual stellar luminosities, because the accretion onto the protostars contributes significantly to the radio emission. After subtracting the accretion luminosity from L *,T84, we obtained reasonable estimates of the stellar luminosity. Using the 0.5 Myr isochrone, we calculated the stellar masses according to the stellar luminosities, and found that they roughly follow the   relation of embedded clusters, consistent with the ionizing sources representing the most massive stars in the embedded clusters of H II-clumps. We also studied the contribution of the possible flaring activity to the observed stellar luminosity and found that they can be neglected. We further studied the change of SFE with the clump mass. According to the derived mass of the most massive star in each HII-clump, using the theoretical   relation, we calculated the mass of the corresponding embedded cluster and then the SFE of the clump. The SFE decreases with increasing clump mass, with a median value of ≍0.3. We also independently derived the SFE for each H II-clump based on the model developed in our previous work. The SFEs of H II-clumps derived from the observation and the model are in good agreement. Concerning the star formation histories of the ATLASGAL clumps, low-mass clumps may reach the peak of star formation earlier than high-mass clumps, consistent with the shorter free-fall time of low-mass clumps.

Keywords: Accretion, Compact H II region, Radio source catalogs, Protoclusters, Young stellar objects
A New Parameterization for Finding Solutions for Microlensing Exoplanet Light Curves. The gravitational microlensing method of discovering exoplanets and multi-star systems can produce degenerate solutions, some of which require in-depth analysis to uncover. We propose a new parameter space that can be used to sample potential solutions more efficiently and is more robust at finding all degenerate solutions for the "central-resonant" caustic degeneracy. We identified two new parameters, k and h, that can be sampled in place of the mass ratios and separations of the systems under analysis to identify degenerate solutions. The parameter k is related to the size of the central caustic, Δξ  c , while h is related to the distance of a point along the k contour from log(s) = 0, where s is the projected planet-host separation. In this work, we present the characteristics of these parameters and the tests we conducted to prove their efficacy.

Keywords: Gravitational microlensing, Gravitational microlensing exoplanet detection, Binary lens microlensing
Parallel Analogy Method for Measuring FRD of the FASOT-IFU. A fiber integral field unit (IFU) was chosen for the Fiber Array Solar Optical Telescope (FASOT) to obtain high-spectral-resolution polarization solar spectral images. This IFU features a dual-array-end design, complemented by a dozen slit ends. Each consists of 2 sub-slits corresponding to the dual array ends. In order to accurately and quickly measure the focal ratio degradation of 8064 fibers in FASOT-IFU, a parallel analogy method (PAM) for FASOT-IFU was proposed. This method primarily relies on characterizing the focal ratio based on the full-width at half-maximum (FWHM) of the fiber's output spot, and the linear relationship between the output focal ratio of the spot and the FWHM. By precisely calculating the focal ratio of the positioning fiber in the FASOT-IFU and treating it as a reference, the output focal ratio of the working fiber can be obtained by comparing the FWHM of the working fiber spot and the positioning fiber spot at the same emission distance. The average value of the output focal ratio by PAM corresponding to the 4032 fibers from Array A of the IFU is 6.0 and the standard deviation is 0.6. The values corresponding to the Array B are 6.2 and 0.40, respectively. The mean value exceeds the contractually specified F/5.5, and the proportion of optical fibers with a focal ratio greater than 5.5 accounts for 88% of the total number of optical fibers, meeting the design requirements of the FASOT system.

Keywords: Astronomical techniques, Astronomical instrumentation, Astronomical methods
Detection Limits of Thermal-infrared Observations with Adaptive Optics. I. Observational Data. Ground-based thermal infrared observations face substantial challenges in correcting the predominant background emitted as thermal radiation from the atmosphere and the telescope itself. With the upcoming 40 m class ELTs, unprecedented sensitivities from ground will be reached, underlining the need of even more sophisticated background correction strategies. This study aims to investigate the impact of thermal backgrounds on ground-based observations and identify possible limiting factors in dedicated correction strategies. We evaluate temporal and spatial characteristics of the thermal background in direct imaging data obtained with different telescopes and observation modes. In particular, three distinct data sets, acquired using VLT/NACO and KECK/NIRC2, are analyzed. Our analysis reveals that the observations are not fully photon shot noise limited, but exhibit additional sensitivity losses caused by imperfect background compensation in the different data sets. We identify correlations between background fluctuations and the activity of the adaptive optics system. We hypothesize that the pupil modulation of the adaptive optics mirrors introduces high frequency spatial and temporal fluctuations to the background, which could ultimately constrain the detection limit if they are not compensated adequately.

Keywords: Infrared astronomy, Calibration, Astronomical instrumentation, Ground-based astronomy, High angular resolution
Multi-amplifier Sensing Charge-coupled Devices for Next Generation Spectroscopy. We present characterization results and performance of a prototype Multiple-Amplifier Sensing (MAS) silicon charge-coupled device (CCD) sensor with 16 channels potentially suitable for faint object astronomical spectroscopy and low-signal, photon-limited imaging. The MAS CCD is designed to reach sub-electron readout noise by repeatedly measuring charge through a line of amplifiers during the serial transfer shifts. Using synchronized readout electronics based on the Dark Energy Spectroscopic Instrument CCD controller, we report a read noise of 1.03 e‑ rms pix‑1 at a speed of 26 μs pix‑1 with a single-sample readout scheme where charge in a pixel is measured only once for each output stage. At these operating parameters, we find the amplifier-to-amplifier charge transfer efficiency (ACTE) to be &gt;0.9995 at low counts for all amplifiers but one for which the ACTE is 0.997. This charge transfer efficiency falls above 50,000 electrons for the read-noise optimized voltage configuration we chose for the serial clocks and gates. The amplifier linearity across a broad dynamic range from ∼300 to 35,000 e‑ was also measured to be ±2.5%. We describe key operating parameters to optimize on these characteristics and describe the specific applications for which the MAS CCD may be a suitable detector candidate.

Keywords: Astronomical detectors, CCD observation, Astronomical instrumentation, Sky surveys
The First Palomar Gattini-IR Catalog of J-band Light Curves: Construction and Public Data Release. Palomar Gattini-IR (PGIR) is a wide-field, synoptic infrared time domain survey covering ≈15,000 sq. deg. of the accessible sky at ≈1–3 night cadence to a depth of J ≈ 13.0 and ≈14.9 Vega mag in and outside the Galactic plane, respectively. Here, we present the first data release of J-band light curves of Two Micron All Sky Survey (2MASS) sources within the survey footprint covering approximately the first four years of operations. We describe the construction of the source catalog based on 2MASS point sources, followed by exposure filtering criteria and forced PSF photometry. The catalog contains light curves of ≈286 million unique sources with 2MASS magnitudes of J &lt; 15.5 mag, with a total of ≈50 billion photometric measurements and ≈20 billion individual source detections at signal-to-noise-ratio &gt; 3. We demonstrate the photometric fidelity of the catalog by (i) quantifying the magnitude-dependent accuracy and uncertainty of the photometry with respect to 2MASS and (ii) comparing against forced PGIR aperture photometry for known variable sources. We present simple filtering criteria for selecting reliable photometric measurements as well as example Python notebooks for users. This catalog is one of the largest compilation of nightly cadence, synoptic infrared light curves to date, comparable to those in the largest optical surveys, providing a stepping stone to upcoming infrared surveys in the coming decade.

Keywords: Transient sources, Time domain astronomy, Near infrared astronomy
Embedded Star Catalog Calculation Tool for Autonomous Star Trackers. Autonomous star trackers are crucial attitude sensors for spacecraft three-axis control. They are the most accurate commercial-off-the-shelf sensors available. An autonomous star tracker is an optoelectronic device that autonomously determines the spacecraft's attitude, using an embedded star catalog that is compared to in-orbit images to perform stellar field recognition. This work presents a computational tool to calculate the embedded star catalog for any specified star sensor. To optimize the star sensor design, the tool developed provides users with sensor accuracy analysis regarding the observed starfield.

Keywords: Artificial satellites, Astronomical instrumentation
Analyzing Stellar Spectra for PRV by Accurate Modeling and Retrieval of Telluric Absorption Features. Ground-based Precision Radial Velocity (PRV) measurements are inevitably impeded by contamination from telluric absorption features, particularly in the infrared region. Thus, it is crucial to improve modeling of the telluric absorption features down to the spectral noise level. As part of the efforts towards improved PRV measurements, we have taken an existing atmospheric trace gas retrieval algorithm (GFIT) and have successfully adapted it to fit the telluric absorption features in stellar spectra down to the spectral noise level (typically ∼1%). We have established a stellar spectral fitting processing pipeline, Stellar-GFIT, to analyze a series of stellar spectra observed by two spectrographs, PARVI (1.1–1.76 μm) commissioned at the Palomar Observatory (Palomar Mountain, CA) and iSHELL (1–5 μm) deployed on the IRTF (Mauna Kea, HI). For this, we have (1) implemented a Gaussian instrumental line shape function, (2) generated atmospheric models (consisting of temperature, pressure, and volume mixing ratios of all the known trace gases) for the particular observation sites and times, (3) employed the most up-to-date spectroscopic parameters in the target spectral regions, and finally (4) developed a series of spectral fitting intervals of ∼60 cm‑1 width, i.e., micro-windows, customized to the individual orders of each spectrograph. Stellar-GFIT is also capable of handling non-telluric features, such as transitions from a gas cell placed in the starlight beam and stellar features if a model spectrum template is available for the target star. We present spectrum fits from the observations of various target stars and discuss the performance and advantages of our novel approach. One of the major strengths of Stellar-GFIT is an ability to adjust the abundance of atmospheric trace gases simultaneously with determining the stellar doppler shift, mitigating any adverse impacts of short-timescale variations of water vapor.

Keywords: Radial velocity, Exoplanet detection methods, Molecular spectroscopy, Spectroscopy
Spectral Performance of the Follow-up X-Ray Telescope on Board the EP Satellite. The Follow-up X-ray Telescope (FXT) is one of the two main scientific instruments on board the Einstein Probe astronomical satellite, which was launched in 2024 January. FXT focuses on the energy range of 0.3–10 keV and mainly conducts follow-up observations of transients and burst sources. It consists of two units of completely independent optical system and detector system (FXT-A and FXT-B). The focal plane detector adopts PNCCD provided by Max Planck Institute for Extraterrestrial Physics. FXT was designed to have three operating modes with different integration times and readout schemes, namely full-frame mode, partial-window mode and timing mode. We conducted a detailed calibration for PNCCD at the Institute of High Energy Physics before launch. Our results demonstrate that both FXT-A and FXT-B exhibit excellent spectral performance. The energy resolution (Full Width at Half Maximum) of FXT-A and FXT-B are both better than 85 eV at 1.487 keV. We determined a mean equivalent noise charge around 2.8 e‑ for FXT-A and FXT-B in three operating modes at ‑90°C ± 0.5°C, except for a few noisy pixels in full-frame mode. In addition, we measured the relation of charge transfer inefficiency as function of photon energy and confirmed the ability to detect photons in the energy range of 0.3–10 keV. These calibration results have been ingested into the initial version of calibration database and applied to the analysis of scientific data acquired by FXT.

Keywords: Calibration, X-ray detectors, Astronomical instrumentation
MAUVE: An Ultraviolet Astrophysics Probe Mission Concept. We present the mission concept "Mission to Analyze the UltraViolet universE" (MAUVE), a wide-field spectrometer and imager conceived during the inaugural NASA Astrophysics Mission Design School. MAUVE responds to the 2023 Announcement of Opportunity for Probe-class missions, with a budget cap of $1 billion, and would hypothetically launch in 2031. However, the formulation of MAUVE was an educational exercise and the mission is not being developed further. The Principle Investigator-led science of MAUVE aligns with the priorities outlined in the 2020 Astrophysics Decadal Survey, enabling new characterizations of exoplanet atmospheres, the early-time light curves of some of the universe's most explosive transients, and the poorly-understood extragalactic background light. Because the Principle Investigator science occupies 30% of the observing time available during the mission's 5 yr lifespan, we provide an observing plan that would allow for 70% of the observing time to be used for General Observer programs, with community-solicited proposals. The onboard detector (THISTLE) claims significant heritage from the Space Telescope Imaging Spectrograph on Hubble, but extends its wavelength range down to the extreme UV. We note that MAUVE would be the first satellite in decades with the ability to access this regime of the electromagnetic spectrum. MAUVE has a field of view of 900″ × 900″, a photometric sensitivity extending to m UV ≤ 24, and a resolving power of R ∼ 1000. This paper provides full science and mission traceability matrices for this concept, and also outlines cost and scheduling timelines aimed at enabling a within-budget mission and an on-time launch.

Keywords: Space telescopes, Extreme ultraviolet astronomy
Design and Performance of the Upgraded Mid-infrared Spectrometer and Imager (MIRSI) on the NASA Infrared Telescope Facility. We describe the new design and current performance of the Mid-InfraRed Spectrometer and Imager (MIRSI) on the NASA Infrared Telescope Facility (IRTF). The system has been converted from a liquid nitrogen/liquid helium cryogen system to one that uses a closed-cycle cooler, which allows it to be kept on the telescope at operating temperature and available for observing on short notice, requiring less effort by the telescope operators and day crew to maintain operating temperature. Several other enhancements have been completed, including new detector readout electronics, an IRTF-style standard instrument user interface, new stepper motor driver electronics, and an optical camera that views the same field as the mid-IR instrument using a cold dichroic mirror, allowing for guiding and/or simultaneous optical imaging. The instrument performance is presented, both with an engineering-grade array used from 2021 to 2023, and a science-grade array installed in the fall of 2023. Some sample astronomical results are also shown. The upgraded MIRSI is a facility instrument at the IRTF available to all users.

Keywords: Infrared astronomy, Spectrometers, Astronomical instrumentation, Infrared photometry
Forbidden Lines are not Quenched. There is no such thing as "quenching" of forbidden lines.

Keywords: History of astronomy, Atomic physics
Database Design for SpExoDisks: A Database and Web Portal for Spectra of Exoplanet-forming Disks. Data access—or the availability of new and archival data for use by the larger community—is key for scientific advancement. How data is presented, searched, and formatted determines accessibility and it can be difficult to find a solution that fits the needs of a given subdiscipline. We present a generalized roadmap for developing a specialty astronomy database with web application based on the development of the Spectra of Exoplanet-forming Disks (SpExoDisks) database (spexodisks.com), which provides infrared spectra of protoplanetary disks. Expertise in an astronomy subdiscipline can provide two necessary components for creating a database: access to a large volume of specialized data and knowledge of how that data should be presented to the community. However, there are a variety of steps and decisions for database development that can fall outside astronomy expertise. Here we offer generalized discussions on design and process that are accompanied by real-world examples from the SpExoDisks developer team and website. Starting from the database portal design and data organization, we demonstrate on-demand data distribution and query using publicly accessible database software. These systems support interactive visualizations such that users can explore spectra directly from their browsers. We also offer details that show how the technical concepts in SpExoDisks are implemented, particularly emphasizing sustainability and long-term management of the codebase and processes. Finally, we illustrate the utility that a specialty website can offer to the community by providing a specific example of how the combined spectra from SpExoDisks can enhance our understanding of protoplanetary disks.

Keywords: Astronomy web services, Computational astronomy, Astronomy databases, Exoplanets, Computational methods, Protoplanetary disks
Discovery of Six Low-z, High-luminosity, and High-mass Quasars. This study presents the discovery of six low-redshift quasars, identified through spectral observations conducted with the RTT-150 telescope. These quasars, with redshifts ranging from 0.3 to 0.6, were selected incorporating their placement in the color–color diagrams and detection by ROSAT 2RXS, focusing on those resembling the spectral energy distribution of a quasar. Our analysis includes detailed modeling of their continuum and emission line properties, which allowed us to estimate their bolometric luminosities, central black hole masses, and Eddington ratios. The findings reveal that these quasars exhibit exceptionally high luminosities and high masses for their redshift values, making them rare examples in the low-redshift quasar population. The results contribute to our understanding of quasar characteristics and their role in probing the structure and evolution of the nearby universe. This research underscores the importance of continued exploration of low-redshift quasars to enhance our knowledge of cosmic evolution and the dynamics of supermassive black holes in the early universe.

Keywords: Supermassive black holes, Spectroscopy, Quasars
Searching for Gravitational Wave Optical Counterparts with the Zwicky Transient Facility: Summary of O4a. During the first half of the fourth observing run (O4a) of the International Gravitational Wave Network, the Zwicky Transient Facility (ZTF) conducted a systematic search for kilonova (KN) counterparts to binary neutron star (BNS) and neutron star–black hole (NSBH) merger candidates. Here, we present a comprehensive study of the five high-significance (False Alarm Rate less than 1 yr‑1) BNS and NSBH candidates in O4a. Our follow-up campaigns relied on both target-of-opportunity observations and re-weighting of the nominal survey schedule to maximize coverage. We describe the toolkit we have been developing, Fritz, an instance of SkyPortal, instrumental in coordinating and managing our telescope scheduling, candidate vetting, and follow-up observations through a user-friendly interface. ZTF covered a total of 2841 deg2 within the skymaps of the high-significance GW events, reaching a median depth of g ≈ 20.2 mag. We circulated 15 candidates, but found no viable KN counterpart to any of the GW events. Based on the ZTF non-detections of the high-significance events in O4a, we used a Bayesian approach, nimbus, to quantify the posterior probability of KN model parameters that are consistent with our non-detections. Our analysis favors KNe with initial absolute magnitude fainter than ‑16 mag. The joint posterior probability of a GW170817-like KN associated with all our O4a follow-ups was 64%. Additionally, we use a survey simulation software, simsurvey, to determine that our combined filtered efficiency to detect a GW170817-like KN is 36%, when considering the 5 confirmed astrophysical events in O3 (1 BNS and 4 NSBH events), along with our O4a follow-ups. Following Kasliwal et al., we derived joint constraints on the underlying KN luminosity function based on our O3 and O4a follow-ups, determining that no more than 76% of KNe fading at 1 mag day‑1 can peak at a magnitude brighter than ‑17.5 mag.

Keywords: Optical observation, Explosive nucleosynthesis, Compact binary stars, Transient detection, Gravitational waves, Compact objects