Sazuna/UAT_keywords huggingface dataset:
Charge-injection Device Imaging of Sirius with Contrast Ratios Greater than 1:26 Million. The intrinsic nature of many astronomical objects, such as binary and multiple systems, exoplanets, circumstellar and debris disks, and quasar host galaxies, introduces challenging requirements for observational instrumentation and techniques. In each case, we encounter situations where the light from bright sources hampers our ability to detect surrounding fainter targets. To explore all features of such astronomical scenes, we must perform observations at the maximum possible contrast ratios. Charge-injection devices (CIDs) are capable of potentially exceeding contrast ratios of ${\mathrm{log}}_{10}(\mathrm{CR})\gt 9$ (i.e., 1 part in 1 billion) due to their unique readout architectures and inherent anti-blooming abilities. An on-sky testing of a commercially available CID, SpectraCAM XDR (SXDR), demonstrated raw contrast ratios from sub-optimal ground-based astronomical observations that imposed practical limits on the maximum achievable contrast ratios using CIDs. Here, we demonstrate the extreme contrast ratio imaging capabilities of the SXDR using observations of Sirius with the 1.0 m Jacobus Kapteyn Telescope, La Palma, Spain. Based on wavelet-based analysis and precise photometric and astrometric calibrations, we report a direct contrast ratio of Δm  r  = 18.54, ${\mathrm{log}}_{10}(\mathrm{CR})=7.41\pm 0.08$ , or 1 part in 26 million. This is an order of magnitude higher compared to the previous CID results.

Keywords: Astronomical techniques, Direct imaging, Astronomical instrumentation, Astronomy data analysis
Application of NASA core Flight System to Telescope Control Software for 2017 Total Solar Eclipse Observation. The core Flight System (cFS), developed by NASA, is a reusable software framework and a set of pluggable software applications that take advantage of the rich heritage of NASA's successful space missions. We applied the cFS to the development of telescope control software for the observation of the 2017 total solar eclipse. Four main modules were developed: imaging control, mechanism control, data handling, and automated observation. Other modules, such as communication and scheduler, were reused from the cFS. Using an integrated observation system, we successfully observed the total solar eclipse, in which the linearly polarized brightness of the solar corona and sky background were measured at four different wavelengths. In this study, we demonstrated the usefulness of the cFS to develop telescope control software through an eclipse observation system, the so-called DICE (DIagnostic Coronagraph Experiment) mission. Our experience and knowledge of the cFS were expanded to a flight software BITSE (Balloon-borne Investigation of Temperature and Speed of Electrons in the corona), the high-altitude scientific balloon mission in 2019. We plan to apply this approach to future solar coronagraph observations, such as CODEX (COronal Diagnostic EXperiment), on the International Space Station. We expect that the cFS can also be applied in telescope control software for ground-and space-based observations.

Keywords: Open source software, Solar eclipses, Solar K corona, Polarimetry
Relative Astrometry in an Annular Field. Background. Relative astrometry at or below the microarcsec level with a 1 m class space telescope has been repeatedly proposed as a tool for exo-planet detection and characterization, as well as for several topics at the forefront of Astrophysics and Fundamental Physics. Aim. This paper investigates the potential benefits of an instrument concept based on an annular field of view, as compared to a traditional focal plane imaging a contiguous area close to the telescope optical axis. Method. Basic aspects of relative astrometry are reviewed as a function of the distribution on the sky of reference stars brighter than G = 12 mag (from Gaia EDR3). Statistics of field stars for targets down to G = 8 mag is evaluated by analysis and simulation. Results. Observation efficiency benefits from prior knowledge on individual targets, since source model is improved with few measurements. Dedicated observations (10-20 hr) can constrain the orbital inclination of exoplanets to a few degrees. Observing strategy can be tailored to include a sample of stars, materialising the reference frame, sufficiently large to average down the residual catalog errors to the desired microarcsec level. For most targets, the annular field provides typically more reference stars, by a factor four to seven in our case, than the conventional field. The brightest reference stars for each target are up to 2 mag brighter. Conclusions. The proposed annular field telescope concept improves on observation flexibility and/or astrometric performance with respect to conventional designs. It appears therefore as an appealing contribution to optimization of future relative astrometry missions.

Keywords: Space vehicle instruments, Astrometric exoplanet detection, Astronomical instrumentation, Space astrometry
Astrometric Precision Tests on TESS Data. Astrometry at or below the microarcsec level with an imaging telescope assumes that the uncertainty on the location of an unresolved source can be an arbitrarily small fraction of the detector pixel, given a sufficient photon budget. This paper investigates the geometric limiting precision, in terms of CCD pixel fraction, achieved by a large set of star field images, selected among the publicly available science data of the Transiting Exoplanet Survey Satellite (TESS) mission. The statistics of the distance between selected bright stars (G ≃ 5 mag), in pixel units, is evaluated, using the position estimate provided in the TESS light curve files. The dispersion of coordinate differences appears to be affected by long term variation and noisy periods, at the level of 0.01 pixel. The residuals with respect to low-pass filtered data (tracing the secular evolution), which are interpreted as the experimental astrometric noise, reach the level of a few milli-pixel or below, down to 1/5900 pixel. Saturated images are present, evidencing that the astrometric precision is mostly preserved across the CCD columns, whereas it features a graceful degradation in the along column direction. The cumulative performance of the image set is a few micropixel across columns, or a few 10 μpx along columns. The idea of astrometric precision down to a small fraction of a CCD pixel, given sufficient signal to noise ratio, is confirmed by real data from an in-flight science instrument to the 10-6 pixel level. Implications for future high precision astrometry missions are briefly discussed.

Keywords: Space telescopes, Astronomical detectors, Optical observation, Space astrometry
The Renovated Thacher Observatory and First Science Results. Located on the campus of the Thacher School in Southern California, the Thacher Observatory has a legacy of astronomy research and education that dates back to the late 1950s. In 2016, the observatory was fully renovated with upgrades including a new 0.7 m telescope, a research grade camera, and a slit dome with full automation capabilities. The low-elevation site is bordered by the Los Padres National Forest and therefore affords dark to very dark skies allowing for accurate and precise photometric observations. We present a characterization of the site including sky brightness, weather, and seeing, and we demonstrate the on-sky performance of the facility. Our primary research programs are based around our multi-band photometric capabilities and include photometric monitoring of variable sources, a nearby supernova search and followup program, a quick response transient followup effort, and exoplanet and eclipsing binary light curves. Select results from these programs are included in this work which highlight the broad range of science available to an automated observatory with a moderately sized telescope.

Keywords: Type Ia supernovae, Astronomical instrumentation, Exoplanets
Research on radiometric calibration of the SVOM Visible Telescope. The Visible Telescope (VT), which is the primary payload for the Chinese-French Space Multi-band Variable Object Monitor (SVOM) mission, is designed to observe the optical afterglow of gamma-ray bursts (GRBs). While calibration is one of the key factors to validate that VT achieves its scientific objectives in terms of detection limit, photometric accuracy and photometric system deviation. In the dissertation, based on the scientific objectives and optomechanical parameters of SVOM VT, the calibration techniques for space-based astronomical telescopes are studied. We have carried out comprehensive characterization and high-precision calibration of VT qualification model in three phases: detector, instrumentation and in-orbit laboratory verification, and all tests have reached the desired results and meet the requirements of calibration indicators.

Keywords: CCD photometry, Astronomy data analysis, Astronomical detectors, Calibration, Space telescopes
Low Mass Stars as Tracers of Star and Cluster Formation. We review the use of young low mass stars and protostars, or young stellar objects (YSOs), as tracers of star formation. Observations of molecular clouds at visible, infrared, radio and X-ray wavelengths can identify and characterize the YSOs populating these clouds, with the ability to detect deeply embedded objects at all evolutionary stages. Surveys with the Spitzer, Herschel, XMM-Newton and Chandra space telescopes have measured the spatial distribution of YSOs within a number of nearby (&lt;2.5 kpc) molecular clouds, showing surface densities varying by more than three orders of magnitude. These surveys have been used to measure the spatially varying star formation rates and efficiencies within clouds, and when combined with maps of the molecular gas, have led to the discovery of star-forming relations within clouds. YSO surveys can also characterize the structures, ages, and star formation histories of embedded clusters, and they illuminate the relationship of the clusters to the networks of filaments, hubs and ridges in the molecular clouds from which they form. Measurements of the proper motions and radial velocities of YSOs trace the evolving kinematics of clusters from the deeply embedded phases through gas dispersal, providing insights into the factors that shape the formation of bound clusters. On 100 pc scales that encompass entire star-forming complexes, Gaia is mapping the young associations of stars that have dispersed their natal gas and exist alongside molecular clouds. These surveys reveal the complex structures and motions in associations, and show evidence for supernova driven expansions. Remnants of these associations have now been identified by Gaia, showing that traces of star-forming structures can persist for a few hundred million years.

Keywords: Star forming regions, Molecular clouds, Pre-main sequence stars, Star formation, Low mass stars, Protostars, Stellar associations, Star clusters
Multiband Emission Properties of 1ES 1959+650. We have systemically studied the properties of 1ES 1959+650, specifically its multiband variability and emission mechanisms. We carefully analyze multiband variability properties by four different kinds of trusted approaches. In contrast with previous research and thanks to our more detailed data, we find that an unprecedented significant quasi-periodic component with timescale $P={266.2}_{-7.2}^{+7.5}$ in the optical R band indeed exists. We suggest that this light curve may result from accretion flow instabilities. Further, among the multiband spectra, we find no significant correlation between different bands, which implies that the physical origin of the dominant radiation for different bands is not the same. Motivated by these results, we go on further to study the radiation mechanisms based on quasi-simultaneous spectra. Here, a model that self-consistently involves protons, electrons, and photons is used to study the light curve and interpret the spectral energy distribution of 1ES 1959+650. Considering the variability properties and model calculation, we suggest that the variation of the cutoff energy of electrons and protons may dominate the variability of X-ray and γ-ray bands in 1ES 1959+650.

Keywords: Non-thermal radiation sources, Active galaxies, BL Lacertae objects
The Spectrum Variabilities of FSRQ 3C 273. 3C 273 is a well-studied FSRQ. In order to analyze its spectrum variabilities, we make spectroscopic observations of 3C 273 using the 2.16 m telescope at Xinglong Observatory of the National Astronomical Observatories. Based on these observations and some other spectra from the literature, we study the spectrum variabilities and the physical origin of the optical spectrum. The main results are as follows: (1) The continuum spectrum (S  c ) shows obvious variabilities and displays quasi-periodic properties, P = 3.39 ± 1.13 yr, consistent with the result calculated from photometric observations. (2) The spectral energy distribution (SED) was modeled by a combination of blackbody emission that originated from the accretion disk and the dusty torus, synchrotron emission from the jet, the synchrotron self-Compton (SSC) emission, and the external Compton (EC) emission from the broad-line region, accretion disk, and dusty torus. The SED suggests that the optical continuum is dominated by the thermal emission from the accretion disk. (3) A time delay of ${\tau }_{c{{\rm{H}}}_{\beta }}=209.42\pm 9.38$ days lies between the slope of the continuum spectrum (S  c ) and H β  emission line. (4) The relationships between the spectrum and polarization can be explained by the jet model.

Keywords: Blazars, Spectrometers, Flat-spectrum radio quasars
A Deep Investigation of Two Poorly Studied Open Clusters Haffner 22 and Melotte 71 in the Gaia era. This paper presents a deep investigation of two open clusters, Haffner 22 and Melotte 71, using astrometric and photometric data from Gaia EDR3. We identified 382 and 597 most probable cluster members with membership probability higher than 50%. Mean proper motions in R.A. and decl. are estimated as (-1.631 ± 0.009, 2.889 ± 0.008) and (-2.398 ± 0.004, 4.210 ± 0.005) mas yr-1 for Haffner 22 and Melotte 71, respectively. A comparison of observed CMDs with the theoretical isochrones leads to an age of 2.25 ± 0.25 and 1.27 ± 0.14 Gyr for these clusters. The distances 2.88 ± 0.10 and 2.28 ± 0.15 kpc based on the parallax are comparable with the values derived by the isochrone fitting method. Five and four blue straggler stars (BSS) are identified as cluster members in Haffner 22 and Melotte 71. Based on the relative number of high-velocity (binary) and single stars, we inferred binary fractions for both clusters in the range of ~10% ≤ f bin ≤ 14%, for both core and o?-core regions. We found binary content is larger in the core region. Mass function slope is in good agreement with the Salpeter's value for Melotte 71 (x = 1.23 ± 0.38 within mass range 1-3.4 M ⊙) while it is quite a flat slope for Haffner 22 (x = 0.63 ± 0.30 within mass range 1-2.3 M ⊙). Evidence for the existence of mass-segregation effect is observed in both clusters. Using the Galactic potential model, Galactic orbits are derived, indicating that both clusters follow a circular path around the Galactic center, evolving slowly.

Keywords: Binary stars, Initial mass function, Stellar dynamics, Open star clusters, Blue straggler stars
The Sensitivity of GPz Estimates of Photo-z Posterior PDFs to Realistically Complex Training Set Imperfections. The accurate estimation of photometric redshifts is crucial to many upcoming galaxy surveys, for example, the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST). Almost all Rubin extragalactic and cosmological science requires accurate and precise calculation of photometric redshifts; many diverse approaches to this problem are currently in the process of being developed, validated, and tested. In this work, we use the photometric redshift code GPz to examine two realistically complex training set imperfections scenarios for machine learning based photometric redshift calculation: (i) where the spectroscopic training set has a very different distribution in color-magnitude space to the test set, and (ii) where the effect of emission line confusion causes a fraction of the training spectroscopic sample to not have the true redshift. By evaluating the sensitivity of GPz to a range of increasingly severe imperfections, with a range of metrics (both of photo-z point estimates as well as posterior probability distribution functions, PDFs), we quantify the degree to which predictions get worse with higher degrees of degradation. In particular, we find that there is a substantial drop-off in photo-z quality when line-confusion goes above ~1%, and sample incompleteness below a redshift of 1.5, for an experimental setup using data from the Buzzard Flock synthetic sky catalogs.

Keywords: Astrostatistics techniques, Photometry, Redshift surveys, Astrostatistics
A Conditional Autoencoder for Galaxy Photometric Parameter Estimation. Astronomical photometric surveys routinely image billions of galaxies, and traditionally infer the parameters of a parametric model for each galaxy. This approach has served us well, but the computational expense of deriving a full posterior probability distribution function is a challenge for increasingly ambitious surveys. In this paper, we use deep learning methods to characterize galaxy images, training a conditional autoencoder on mock data. The autoencoder can reconstruct and denoise galaxy images via a latent space engineered to include semantically meaningful parameters, such as brightness, location, size, and shape. Our model recovers galaxy fluxes and shapes on mock data with a lower variance than the Hyper Suprime-Cam photometry pipeline, and returns reasonable answers even for inputs outside the range of its training data. When applied to data in the training range, the regression errors on all extracted parameters are nearly unbiased with a variance near the Cramr-Rao bound.

Keywords: Galaxy photometry, Galaxy classification systems, Photometry
Update on the Systematics in the ALMA Proposal Review Process After Cycle 8. We present an updated analysis of systematics in the Atacama Large Millimeter/submillimeter Array (ALMA) proposal ranks to include the last two ALMA cycles, when significant changes were introduced in the proposal review process. In Cycle 7, the investigator list on the proposal cover sheet was randomized such that the reviewers were aware of the overall proposal team but did not know the identity of the principal investigator (PI). In Cycle 8, ALMA adopted distributed peer review for most proposals and implemented dual-anonymous review for all proposals, in which the identity of the proposal team was not revealed to the reviewers. The most significant change in the systematics in Cycles 7 and 8 compared to previous cycles is related to the experience of PIs in submitting ALMA proposals. PIs that submit a proposal every cycle tend to have ranks that are consistent with average in Cycles 7 and 8, whereas previously they had the best overall ranks. Also, PIs who submitted a proposal for the second time show improved ranks over previous cycles. These results suggest some biases related to the relative prominence of the PI have been present in the ALMA review process. Systematics related to regional affiliation remain largely unchanged in that PIs from Chile, East Asia, and non-ALMA regions tend to have poorer overall ranks than PIs from Europe and North America. The systematics of how one region ranks proposals from another region are also investigated. No significant differences in the overall ranks based on gender of the PI are observed.

Keywords: Telescopes
Wayne State University's Dan Zowada Memorial Observatory: Characterization and Pipeline of a 0.5 m Robotic Telescope. Wayne State University's Dan Zowada Memorial Observatory is a fully robotic 0.5 m telescope and imaging system located under the dark skies of New Mexico. The observatory is particularly suited to time domain astronomy: the observation of variable objects, such as tidal disruption events, supernovae, and active galactic nuclei. We have developed a software suite for image reduction, alignment and stacking, and calculation of absolute photometry in the Sloan filters used at the telescope. Our pipeline also performs image subtraction to enable photometry of objects embedded in bright backgrounds such as galaxies. The 5σ detection limit of the Zowada Observatory for integration of 16 × 90 s exposures is 19.0 mag in g-band, 18.1 mag in r-band, 17.9 mag in i-band, and 16.6 mag in z-band. For a 3σ detection limit, measurements may be performed with greater uncertainties as deep as 19.9, 19.1. 18.9 and 17.5 mag in griz bands, respectively.

Keywords: CCD photometry, Astronomy software, Observatories, Light curves, Calibration, Burkert profile, Sloan photometry, Optical observatories
Initial Ni-56 Masses in Type Ia Supernovae. We infer initial masses of the synthesized radioactive nickel-56 in a sample of recent Type Ia supernovae applying a new formalism introduced recently by Khatami &amp; Kasen. It is shown that the nickel masses we derive do not differ significantly from previous estimates based on the traditional Arnett-model. We derive the β parameter for our sample SNe and show that these are consistent with the fiducial value of ~1.6 given by Khatami &amp; Kasen from SN Ia hydrodynamical simulations.

Keywords: Explosive nucleosynthesis, Type Ia supernovae, Radiative transfer
V505 Cyg: A Mass-transferring Marginal Contact Binary. High-precision photometric data of V505 Cyg from TESS and one spectrum observed by us are presented in this work, and the stellar atmospheric parameters of the primary component were derived via spectral fitting. Applying the Wilson-Devinney code, the photometric elements were computed for the first time. The results show V505 Cyg is a near contact binary with the primary filling its Roche Lobe and the secondary a little under-filling, along with the temperature difference of about ΔT = 1900 K between the two components. The eclipse is total and lasts for about 90 minutes, which is about 0.1 phase, so the photometric results are reliable. This system belongs to near-contact binaries with the light curves enhanced around the left shoulder of the secondary minimum, which can be explained by a hot spot on the secondary components due to mass transfer, via a stream from the primary components hitting the facing surface of the secondary components. Meanwhile, we conducted an orbital period investigation of it in detail. The orbital period study based on all times of minimum including 230 new ones determined by us reveals a secular period decreasing at the rate of dP/dt = -2.31 × 10-7 d · yr-1. The decrease of the orbital period can be the result of mass transfer between the components, agreeing well with the configuration and the asymmetric light curves of V505 Cyg. V505 Cyg is therefore another rare example of mass transferring marginal contact binary lying on the rapid evolutionary stage predicted by the Thermal Relaxation Oscillation theory. With the orbital period decrease, V505 Cyg will evolve into an overcontact binary.

Keywords: Close binary stars, Eclipsing binary stars, Binary stars