Sazuna/UAT_keywords huggingface dataset:
Probing the Atmospheric Precipitable Water Vapor with SOFIA, Part III. Atlas of Seasonal Median PWV Maps from ERA5, Implications for FIFI-LS and in situ Comparison Between the ERA5 and MERRA-2 Atmospheric Re-analyses. The Stratospheric Observatory for Infrared Astronomy (SOFIA) is an airborne observatory for far-infrared astronomy stationed at the Armstrong Flight Research Center (AFRC) in Palmdale, CA, USA. Although SOFIA flies at altitudes of ~41,000 ft, any far-infrared observations from within the Earth's atmosphere are nevertheless hampered by water vapor absorbing the astronomical signal. The primary atmospheric parameter governing absorption in the far-infrared is the total upward precipitable water vapor, PWV. In this paper we present global PWV maps derived from re-analyses from the European Centre for Medium-Range Weather Forecasts, ECMWF, with a geographical resolution of 0.°5, for flight altitudes ranging from 37,000 ft to 45,000 ft and each meteorological season. These maps were validated with FIFI-LS PWV measurements on board SOFIA and allow an investigation of the global morphology and seasonal dependence of the total upward PWV in the stratosphere. We additionally investigate the observing conditions, in terms of PWV, at various locations, especially around SOFIA's home base, Palmdale, but also around sites in the southern hemisphere like Tahiti, Santiago de Chile (Chile), Buenos Aires (Argentina), and Christchurch (New Zealand). From the southern sites investigated Christchurch provides the best conditions in terms of PWV (and efficiency), Tahiti the worst. Using total power sky measurements with FIFI-LS we also derive a mean emissivity of the telescope (primary, secondary and tertiary mirror) of ϵ Tel = 20.5 ± 1.6% around the astronomically significant [C II] emission line. We finally compare atmospheric re-analyses from GEOS (MERRA-2) and ECMWF (ERA5) to our FIFI-LS PWV measurements. Both re-analyses correlate linearly with our FIFI-LS PWV measurements from all flight altitudes but with different scaling factors. However, MERRA-2 correlates significantly less well than ERA5 especially for flight altitudes below 41,000 ft.

Keywords: Atmospheric extinction, Astronomy data analysis, Astronomical instrumentation, Astronomical methods, Astronomy data reduction
TANSPEC: TIFR-ARIES Near-infrared Spectrometer. We present the design and performance of the TANSPEC, a medium-resolution 0.55-2.5 μm cryogenic spectrometer and imager, now in operation at the 3.6 m Devasthal Optical Telescope (DOT), Nainital, India. The TANSPEC provides three modes of operation, which include photometry with broad- and narrowband filters, spectroscopy with short slits of 20″ length and different widths (from 0.″5 to 4.″0) in cross-dispersed mode at a resolving power R of ~2750, and spectroscopy with long slits of 60″ length and different widths (from 0.″5 to 4.″0) in prism mode at a resolving power R of ~100-350. TANSPEC's imager mode provides a field of view of 60″ × 60″ with a plate scale of 0.″245 pixel-1 on the 3.6 m DOT. The TANSPEC was successfully commissioned during 2019 April-May, and the subsequent characterization and astronomical observations are presented here. The TANSPEC was made available to the worldwide astronomical community for science observations from 2020 October.

Keywords: Spectrometers, Optical observation, Direct imaging, Near infrared astronomy
SMC-Last Mosaic Images. We present mosaic images of the Small Magellanic Cloud (SMC) observed with the Spitzer IRAC 3.6 μm and 4.5 μm bands over two epochs, 2017 August 25-2017 September 13 and 2017 November 24-2018 February 12. The survey region comprises ~30 deg2 covering the SMC and the Bridge to the Large Magellanic Cloud. The region is covered by 52 ~ 1.°1 × 1.°1 tiles, with each tile including images in each band for both separate and combined epochs. The mosaics are made in individual tangent projections in J2000 coordinates. The angular pixel size is 0.″6 with a resolution (FWHM) of ~2.″0. We describe processing to correct or mitigate residual artifacts and remove background discontinuities. The mosaic images are publicly available at the Infrared Science Archive.

Keywords: Infrared astronomy, Small Magellanic Cloud
The Unusual Active Galaxy H1821+643 and the Elusive Nature of FRI Quasars. The moderate spin estimate for the black hole at the center of the cool core cluster H1821+643 motivates the completion of a story about this object's origin and evolution that was in the making since the work by Blundell &amp; Rawlings over two decades ago as the first example of a massive black hole accreting at near-Eddington rates with an FRI jet. This elusive combination of properties was explained in our 2010 model where we showed it to be part of a small parameter space that includes X-shaped radio galaxies. As an accreting black hole that never experienced a counterrotating phase, H1821+643 is constrained by theory to produce a jet for spin values a satisfying 0.1 &lt; a &lt; ~ 0.7 and an FRI jet for a slightly smaller range. The feedback from such a black hole is not subject to a tilted jet and is why star formation rates remain high in this cluster environment. The prediction is that H1821+643 is within millions of years of becoming jetless.

Keywords: Radio loud quasars, Quasars
Peculiar Black Hole Accretion Rates in AGN with Highest Star Formation Rates in the Universe. Pouliasis et al. explored star formation rates, black hole accretion rates, and stellar mass of active galaxies at redshift above 3.5, uncovering a leveling off of the star formation rate at high stellar mass, which they consider to be evidence of AGN feedback. Their data shows that as AGN approach the flattening of the curve in the star formation rate-stellar mass plane, the accretion rates begin to drop. We describe the nature of the AGN feedback responsible for this in terms of powerful FRII jets enhancing star formation rates but eventually also triggering a shift in accretion from near-Eddington rates to advection dominated. These systems are on the cusp of a dramatic transition where the active galaxy goes from strong enhancement to large suppression of star formation in a way that produces the steeper slope for radio AGN at low redshift compared to radio AGN at higher redshift and to jetless AGN. We argue, therefore, that the data of Pouliasis et al. constitute the high redshift objects predicted by Singh et al. that connect to the low redshift behavior of radio AGN shown in Comerford et al.

Keywords: Radio loud quasars, Radio quiet quasars, Quasars
KMTNet Nearby Galaxy Survey: Overview and Survey Description. Recently, there has been increasing demand for deep imaging surveys to investigate the history of the mass assembly of galaxies in detail by examining the remnants of mergers and accretions, both of which have very low surface brightness (LSB). In addition, the nature of star formation in LSB regions, such as galaxy outer disks, is also an intriguing topic in terms of understanding the physical mechanisms of disk evolution. To address these issues, this study conducted a survey project, called the Korea Microlensing Telescope Network Nearby Galaxy Survey, to construct a deep imaging data set of nearby galaxies in the southern hemisphere. It provides deep and wide-field images with a field of view of ~12 deg2 for 13 nearby galaxies drawn from the Carnegie-Irvine Galaxy Survey catalog in optical broad bands (BRI) and an Hα narrow band. Through a dedicated data reduction, the surface brightness limit in 10″ × 10″ boxes was found to reach as deep as μ 1σ  ~ 29-31 mag arcsec-2 in the optical broad bands and f 1σ  ~ 1-2 × 10-18 erg s-1 cm-2 arcsec-2 in the Hα narrow band. To conclude the paper, several possible scientific applications for this data set are described.

Keywords: Astronomy databases, Photometry, Astronomy data reduction, Galaxy properties
A New Polar Ring Galaxy Discovered in the COSMOS Field. In order to understand the formation and evolution of galaxies fully, it is important to study their three-dimensional gravitational potential for a large sample of galaxies. Since polar-ring galaxies (PRGs) provide useful laboratories for this investigation, we have started our detailed study of a sample of known PRGs by using the data set obtained by the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP). During the course of this study, we have discovered a new PRG, identified as SDSS J095351.58+012036.1. Its photometric redshift is estimated as z ~ 0.2. The polar ring structure in this PRG appears to be almost perpendicular to the disk of its host galaxy without any disturbed features. Therefore, this PRG will provide us with useful information on the formation of such an undisturbed polar structure. We discuss its photometric properties in detail.

Keywords: Galaxy structure, Galaxy colors, Galaxy photometry
BURSTT: Bustling Universe Radio Survey Telescope in Taiwan. Fast Radio Bursts (FRBs) are bright millisecond-duration radio transients that appear about 1000 times per day, all-sky, for a fluence threshold 5 Jy ms at 600 MHz. The FRB radio-emission physics and the compact objects involved in these events are subjects of intense and active debate. To better constrain source models, the Bustling Universe Radio Survey Telescope in Taiwan (BURSTT) is optimized to discover and localize a large sample of rare, high-fluence, and nearby FRBs. This population is the most amenable to multi-messenger and multi-wavelength follow-up, which allows a deeper understanding of source mechanisms. BURSTT will provide horizon-to-horizon sky coverage with a half power field-of-view (FoV) of ~104 deg2, a 400 MHz effective bandwidth between 300 and 800 MHz, and subarcsecond localization, which is made possible using outrigger stations that are hundreds to thousands of km from the main array. Initially, BURSTT will employ 256 antennas. After tests of various antenna designs and optimizing the system's performance, we plan to expand to 2048 antennas. We estimate that BURSTT-256 will detect and localize ~100 bright (≥100 Jy ms) FRBs per year. Another advantage of BURSTT's large FoV and continuous operation will be its greatly enhanced monitoring of FRBs for repetition. The current lack of sensitive all-sky observations likely means that many repeating FRBs are currently cataloged as single-event FRBs.

Keywords: Very long baseline interferometry, Astronomical instrumentation, Wide-field telescopes, Radio transient sources
Optical Time-series Photometry of the Symbiotic Nova V1835 Aquilae. We present time-series CCD photometry in the BVRI passbands of the recently identified symbiotic nova V1835 Aquilae (NSV 11749) over an interval of 5.1 yr with 7-14 day cadence, observed during its quiescence. We find slow light variations with a range of ~0.9 mag in V and ~0.3 mag in I. Analysis of these data show strong periodicity at 419 ± 10 days, which we interpret to be the system's orbital period. A dip in the otherwise-sinusoidal phased light curve suggests a weak ellipsoidal effect due to tidal distortion of the giant star, which in turn opens the possibility that V1835 Aql transfers some of its mass to the hot component via Roche lobe overflow rather than via a stellar wind. We also find evidence that V1835 Aql is an S-type symbiotic star, relatively free of circumstellar dust, and include it among the nuclear burning group of symbiotics. Finally, we provide photometry, periods, and light curve classifications for 22 variable stars in the field around V1835 Aql, about half of which are newly identified.

Keywords: Photometry, Symbiotic binary stars, Symbiotic novae, Variable stars
FERIA: Flat Envelope Model with Rotation and Infall under Angular Momentum Conservation. Radio observations of low-mass star formation in molecular spectral lines have rapidly progressed since the advent of the Atacama Large Millimeter/submillimeter Array (ALMA). The gas distribution and its kinematics within a few hundreds of astronomical unit scale around a Class 0-I protostar are spatially resolved, and the region where a protostellar disk is being formed is now revealed in detail. In such studies, it is essential to characterize the complex physical structure around a protostar consisting of an infalling envelope, a rotationally supported disk, and an outflow. For this purpose, we have developed a general-purpose computer code "FERIA" (Flat Envelope model with Rotation and Infall under Angular momentum conservation) to generate the image data cube based on the infalling-rotating envelope model and the Keplerian disk model, both of which are often used in observational studies. In this paper, we present the description and the user manual of FERIA and summarize caveats in actual applications. This program outputs cube FITS files, which can be used for direct comparison with observations. It can also be used to generate mock data for machine/deep learning. Examples of these applications are described and discussed to demonstrate how the model analyses work with actual observational data.

Keywords: Interstellar line emission, Bok globules, Young stellar objects, Protoplanetary disks, Protostars
The Variable Earth's Rotation in the 4th-7th Centuries: New ΔT Constraints from Byzantine Eclipse Records. As one of the greatest astronomical spectacles, total solar eclipses have long been a subject of scientific interest and have been recorded by numerous civilizations over the millennia. These records are an essential reference for constraining and reconstructing Earth's variable rotation (ΔT) prior to the 17th century. However, ΔT reconstructions for the 4th-7th centuries have significant uncertainties, mainly owing to a data scarcity. Here, we analyze Byzantine historical sources with reports of total solar eclipses along the Eastern Mediterranean coasts and add probable ΔT constraints on their basis. We examined five cases of total solar eclipses in 346, 418, 484, 601, and 693 CE, identified times and locations of the observations, and compared them with the existing ΔT spline curve to derive new ΔT constraints. Our results probably tighten ΔT variability in 346 CE, show a larger ΔT range in 418 CE, and give smaller ΔT ranges in 484, 601, and 693 CE. Our study tightens the existing ΔT variations and occasionally support some ΔT constraints that slightly depart from the ΔT spline curve in the latest reconstructions. Our results are consistent with contemporary ΔT constraints from other studies and offer an improved understanding of Earth's variable rotation.

Keywords: Eclipses, Solar eclipses, Total eclipses, Earth (planet)
Identifying Transient Candidates in the Dark Energy Survey Using Convolutional Neural Networks. The ability to discover new transient candidates via image differencing without direct human intervention is an important task in observational astronomy. For these kind of image classification problems, machine learning techniques such as Convolutional Neural Networks (CNNs) have shown remarkable success. In this work, we present the results of an automated transient candidate identification on images with CNNs for an extant data set from the Dark Energy Survey Supernova program, whose main focus was on using Type Ia supernovae for cosmology. By performing an architecture search of CNNs, we identify networks that efficiently select non-artifacts (e.g., supernovae, variable stars, AGN, etc.) from artifacts (image defects, mis-subtractions, etc.), achieving the efficiency of previous work performed with random Forests, without the need to expend any effort in feature identification. The CNNs also help us identify a subset of mislabeled images. Performing a relabeling of the images in this subset, the resulting classification with CNNs is significantly better than previous results, lowering the false positive rate by 27% at a fixed missed detection rate of 0.05.

Keywords: Random Forests, Convolutional neural networks, Type Ia supernovae
ATOCA: an Algorithm to Treat Order Contamination. Application to the NIRISS SOSS Mode. After a successful launch, the James Webb Space Telescope is preparing to undertake one of its principal mission objectives, the characterization of the atmospheres of exoplanets. The Single Object Slitless Spectroscopy (SOSS) mode of the Near Infrared Imager and Slitless Spectrograph (NIRISS) is the only observing mode that has been specifically designed for this objective. It features a wide simultaneous spectral range (0.6-2.8 μm) through two spectral diffraction orders. However, due to mechanical constraints, these two orders overlap slightly over a short range, potentially introducing a "contamination" signal in the extracted spectrum. We show that for a typical box extraction, this contaminating signal amounts to 1% or less over the 1.6-2.8 μm range (order 1), and up to 1% over the 0.85-0.95 μm range (order 2). For observations of exoplanet atmospheres (transits, eclipses or phase curves) where only temporal variations in flux matter, the contamination signal typically biases the results by order of 1% of the planetary atmosphere spectral features strength. To address this problem, we developed the Algorithm to Treat Order ContAmination (ATOCA). By constructing a linear model of each pixel on the detector, treating the underlying incident spectrum as a free variable, ATOCA is able to perform a simultaneous extraction of both orders. We show that, given appropriate estimates of the spatial trace profiles, the throughputs, the wavelength solutions, as well as the spectral resolution kernels for each order, it is possible to obtain an extracted spectrum accurate to within 10 ppm over the full spectral range.

Keywords: Astronomy data modeling, Astronomy data reduction, Transmission spectroscopy, Space telescopes, Exoplanet atmospheres, Spectrophotometry
Digitization, Measurement, and Analysis of a 1905 Barnard Atlas Photographic Plate. In the second paper in this series, we improve on our previous demonstration of the ability of a commercially available graphic arts scanner and cost-effective analysis tools to produce scientifically useful scans of astronomical photographic plates. We describe a method using freely available tools to extract magnitude measurements from the star images on sky-survey plates, such as are stored in observatory archives around the world. We detail the use of this method on one plate in particular, Plate 8 in E. E. Barnard's A Photographic Atlas of Selected Regions of the Milky Way, examine the effects of our scanning method on our magnitude measurements, discuss the difficulties encountered when measuring the magnitudes of stars in crowded fields, and present a case study of red supergiant stars appearing within the field. Our work results in a catalog of more than 66,000 measurements of stellar positions and magnitudes in the central 6.°8 × 6.°8 field of view.

Keywords: Surveys, Star atlases, Astrometry, Variable stars, Photographic photometry, Milky Way Galaxy, Catalogs
Climate Change and Astronomy: A Look at Long-term Trends on Maunakea. Maunakea is one of the world's primary sites for astronomical observing, with multiple telescopes operating over submillimeter to optical wavelengths. With its summit higher than 4200 m above sea level, Maunakea is an ideal location for astronomy, with a historically dry, stable climate and minimal turbulence above the summit. Under a changing climate, however, we ask how the (above-)summit conditions may have evolved in recent decades since the site was first selected as an observatory location and how future-proof the site might be to continued change. We use data from a range of sources, including in situ meteorological observations, radiosonde profiles, and numerical reanalyses to construct a climatology at Maunakea over the previous 40 yr. We are interested in both the meteorological conditions (e.g., wind speed and humidity) and the image quality (e.g., seeing). We find that meteorological conditions were, in general, relatively stable over the period with few statistically significant trends and with quasi-cyclical interannual variability in astronomically significant parameters such as temperature and precipitable water vapor. We do, however, find that maximum wind speeds have increased over the past decades, with observed wind speeds above 15 m s-1 increasing in frequency by 1%-2%, which may have a significant impact on ground-layer turbulence. Further, we note that while the conditions themselves are not necessarily changing significantly, the combination of conditions that lead to dome closures (i.e., freezing conditions, increased summit wind speeds, and/or high humidities) are worsening to the point that the number of closure conditions have more than doubled in the last 20 yr. Importantly, we find that the Fried parameter has not changed in the last 40 yr, suggesting there has not been an increase in optical turbulence strength above the summit. Ultimately, more data and data sources-including profiling instruments-are needed at the site to ensure continued monitoring into the future and to detect changes in the summit climate.

Keywords: Observatories, Astronomical instrumentation, Earth atmosphere
The JWST Early Release Science Program for the Direct Imaging and Spectroscopy of Exoplanetary Systems. The direct characterization of exoplanetary systems with high-contrast imaging is among the highest priorities for the broader exoplanet community. As large space missions will be necessary for detecting and characterizing exo-Earth twins, developing the techniques and technology for direct imaging of exoplanets is a driving focus for the community. For the first time, JWST will directly observe extrasolar planets at mid-infrared wavelengths beyond 5 μm, deliver detailed spectroscopy revealing much more precise chemical abundances and atmospheric conditions, and provide sensitivity to analogs of our solar system ice-giant planets at wide orbital separations, an entirely new class of exoplanet. However, in order to maximize the scientific output over the lifetime of the mission, an exquisite understanding of the instrumental performance of JWST is needed as early in the mission as possible. In this paper, we describe our 55 hr Early Release Science Program that will utilize all four JWST instruments to extend the characterization of planetary-mass companions to ~15 μm as well as image a circumstellar disk in the mid-infrared with unprecedented sensitivity. Our program will also assess the performance of the observatory in the key modes expected to be commonly used for exoplanet direct imaging and spectroscopy, optimize data calibration and processing, and generate representative data sets that will enable a broad user base to effectively plan for general observing programs in future Cycles.

Keywords: Coronagraphic imaging, Direct imaging, Space telescopes, Exoplanet detection methods, Exoplanet atmospheres