Sazuna/UAT_keywords huggingface dataset:
Variability and Spectral Behavior of Gamma-Ray Flares of 3C 279. 3C 279 showed enhanced flux variations in Fermi-LAT γ-ray observations from 2018 January to June. We present a detailed Fermi-LAT analysis to investigate the variability and spectral behaviors of 3C 279 during the γ-ray flares in 2018. In this work, we analyzed the γ-ray spectra and found that the spectra in either the flaring or quiescent states do not show any clear breaks (or cutoffs). This indicates that the dissipation region is outside the broad-line region, and the energy dissipation may be due to the inverse Compton process of scattering the dust torus infrared photons, this result is also consistent with that in Tolamatti et al. An external inverse Compton scattering of dusty torus (DT) photons is employed to calculate the broadband spectral energy distribution (SED). This model was further supported by the fact that we found flare decay timescale was consistent with the cooling time of relativistic electrons through DT photons. During the SED modeling, a relatively harder spectrum for the electron energy distribution is found and suggests these electrons may not be accelerated by the shock that happened in the dissipation region. Besides, the magnetic reconnection is also ruled out due to a low magnetization ratio. Thus, we suggest an injection of higher-energy electrons from outside the blob and raising the flare.

Keywords: Galaxy jets, Active galaxies, Gamma-rays, Quasars
Rogue Planets and Brown Dwarfs: Predicting the Populations Free-floating Planetary Mass Objects Observable with JWST. Free-floating (or rogue) planets are planets that are liberated (or ejected) from their host systems. Although simulations predict their existence in substantial numbers, direct observational evidence for free-floating planets with masses below ~5 M Jup is still lacking. Several cycle-1 observing programs with JWST aim to hunt for them in four different star-forming clusters. These surveys are designed to be sensitive to masses of 1-15 M Jup (assuming a hot-start formation), which corresponds to spectral types of early L to late T for the ages of these clusters. If the existing simulations are not wide off the mark, we show here that the planned programs are likely to find up to 10-20 giant rogue planets in moderate density clusters like NGC1333 or IC348, and several dozen to ~100 in high-density regions like NGC2024 and the Orion Nebula Cluster. These numbers correspond to 1%-5% of the total cluster population; they could be substantially higher if stars form multiple giant planets at birth. In contrast, the number of free-floating brown dwarfs, formed from core collapse (like stars) is expected to be significantly lower, only about 0.25% of the number of stars, or 1-7 for the clusters considered here. Below 10 M Jup that number drops further by an order of magnitude. We also show that the planned surveys are not at risk of being significantly contaminated by field brown dwarfs in the foreground or background, after spectroscopic confirmation. Taken together, our results imply that if a population of L and T dwarfs were to be found in these JWST surveys, it is expected to be predominantly made up of rogue planets.

Keywords: Brown dwarfs, Initial mass function, Free floating planets, Infrared observatories, Exoplanet formation
Model-based Performance Characterization of Software Correlators for Radio Interferometer Arrays. Correlation for radio interferometer array applications, including Very Long Baseline Interferometry (VLBI), is a multidisciplinary field that traditionally involves astronomy, geodesy, signal processing, and electronic design. In recent years, however, high-performance computing has been taking over electronic design, complicating this mix with the addition of network engineering, parallel programming, and resource scheduling, among others. High-performance applications go a step further by using specialized hardware like Graphics Processing Units (GPUs) or Field Programmable Gate Arrays (FPGAs), challenging engineers to build and maintain high-performance correlators that efficiently use the available resources. Existing literature has generally benchmarked correlators through narrow comparisons on specific scenarios, and the lack of a formal performance characterization prevents a systematic comparison. This combination of ongoing increasing complexity in software correlation together with the lack of performance models in the literature motivates the development of a performance model that allows us not only to characterize existing correlators and predict their performance in different scenarios but, more importantly, to provide an understanding of the trade-offs inherent to the decisions associated with their design. In this paper, we present a model that achieves both objectives. We validate this model against benchmarking results in the literature, and provide an example for its application for improving cost-effectiveness in the usage of cloud resources.

Keywords: Theoretical models, Astronomy software, Distributed computing, Interferometric correlation, Radio interferometry, Radio astronomy
APPLESOSS: A Producer of ProfiLEs for SOSS. Application to the NIRISS SOSS Mode. The SOSS mode of the Near Infrared Imager and Slitless Spectrograph instrument is poised to be one of the workhorse modes for exoplanet atmosphere observations with the newly launched James Webb Space Telescope (JWST). One of the challenges of the SOSS mode, however, is the physical overlap of the first two diffraction orders of the G700XD grism on the detector. Recently, the ATOCA algorithm was developed and implemented as an option in the official JWST pipeline, as a method to extract SOSS spectra by decontaminating the detector-that is, separating the first and second orders. Here, we present A Producer of ProfiLEs for SOSS (APPLESOSS), which generates the spatial profiles for each diffraction order upon which ATOCA relies. We validate APPLESOSS using simulated SOSS time series observations of WASP-52 b, and compare it to ATOCA extractions using two other spatial profiles (a best and worst case scenario on-sky), as well as a simple box extraction performed without taking into account the order contamination. We demonstrate that APPLESOSS profiles retain a high degree of fidelity to the true underlying spatial profiles, and therefore yield accurate extracted spectra. We further confirm that the effects of the order contamination for relative measurements (e.g., exoplanet transmission or emission observations) is small-the transmission spectrum obtained from each of our four tests, including the contaminated box extraction, is consistent at the ~1σ level with the atmosphere model input into our noiseless simulations. We further confirm via a retrieval analysis that the atmosphere parameters (metallicity and C/O) obtained from each transmission spectrum are consistent with the true underlying values.

Keywords: Exoplanets, Astronomy data analysis, Transmission spectroscopy, Astronomical techniques, Exoplanet atmospheres
A Fast and High-precision Alignment Method for IFU Based on Optical Interferometry and Fresnel Diffraction. High-precision alignment between the microlens array and the fiber-positioning microplate is of great significance in developing fiber-based integrated field units (IFU). In this paper, we propose a method combining optical interference and a Fresnel diffraction model to realize fast and accurate alignment. The minimum resolution angles of the tip and tilt in the optical interference-assisted alignment experiment are 2.6 × 10-4° and 1.3 × 10-4°, respectively. The errors in the remaining four degrees of freedom, x, y, z, and roll, are simulated by the Fresnel diffraction model. Finally, the output energy of 96.7% of the number of fibers is within a tolerance error of 10% and the relative energy reaches its highest level, which meets the IFU requirement.

Keywords: Optical interferometry, Astronomical techniques, Astronomical instrumentation, Solar instruments
SPECULOOS Northern Observatory: Searching for Red Worlds in the Northern Skies. SPECULOOS is a ground-based transit survey consisting of six identical 1 m robotic telescopes. The immediate goal of the project is to detect temperate terrestrial planets transiting nearby ultracool dwarfs (late M-dwarf stars and brown dwarfs), which could be amenable for atmospheric research with the next generation of telescopes. Here, we report the developments of the northern counterpart of the project-SPECULOOS Northern Observatory, and present its performance during the first three years of operations from mid-2019 to mid-2022. Currently, the observatory consists of one telescope, which is named Artemis. The Artemis telescope demonstrates remarkable photometric precision, allowing it to be ready to detect new transiting terrestrial exoplanets around ultracool dwarfs. Over the period of the first three years after the installation, we observed 96 objects from the SPECULOOS target list for 6000 hr with a typical photometric precision of 0.5%, and reaching a precision of 0.2% for relatively bright non-variable targets with a typical exposure time of 25 s. Our weather downtime (clouds, high wind speed, high humidity, precipitation and/or high concentration of dust particles in the air) over the period of three years was 30% of overall night time. Our actual downtime is 40% because of additional time loss associated with technical problems.

Keywords: M dwarf stars, Brown dwarfs, Exoplanets, Photometry, Automated telescopes, Astronomical seeing, Telescopes
An Improved Radio Pointing Model for SHARC II of the Caltech Submillimeter Observatory Telescope. In this research, we develop a new method of upgrading the radio pointing model of an important instrument of the Caltech Submillimeter Observatory (CSO) telescope, i.e., the Submillimeter High Angular Resolution Camera II (SHARC II), by making three types of structural reconstruction of its existing model. First, the axial displacement of the secondary reflector of the telescope is introduced to the radio pointing model for SHARC II. Second, the multi-layer perceptron is applied for better describing higher-order terms in the radio pointing model, which are hard to be mathematically formulated. Third, a receding horizon modeling method is proposed to replace the time-dependent term in the existing model, for better reducing the negative impact of the time drift on the model's accuracy. Results of numerical experiments and statistical significance analysis based on the real pointing data of SHARC II show that the reconstructed radio pointing model can improve the accuracy of estimating the pointing error, and the proposed method of upgrading the radio pointing model is effective. Considering that the CSO telescope will be moved from the old site at Maunakea, Hawaii to the new site at the Chajnantor Plateau in Chile, the proposed methods of upgrading the radio pointing model are expected to be employed for pointing correction after the telescope is refurbished at the new site.

Keywords: Pointing error, Neural networks, Radio telescopes, Submillimeter astronomy, High angular resolution
Is Jet Re-orientation the Elusive Trigger for Star Formation Suppression in Radio Galaxies?. Jet re-orientation associated with the time evolution of radio quasars explains the formation of X-shaped radio galaxies and their preference for isolated environments. But since X-shaped radio galaxies are generally not found in dense environments (e.g., groups/clusters), the jet re-orientation phenomenon for radio galaxies in groups and clusters has been ignored. We take a closer look at the re-orientation of FRI jets with respect to FRII jets, and find that it may constitute the as-yet unidentified trigger for star formation suppression in radio galaxies. We show how the recently explored radio "red geyser" galaxies can be interpreted in this context and ultimately reveal a deeper understanding of why FRII radio galaxies are on one side of the star formation enhancement/suppression divide compared to FRI radio galaxies.

Keywords: Relativistic jets, Star formation
Revisiting the Magnetic Field Distribution of Normal Pulsars: Implications for the Multiple Origins for Neutron Stars. In this study, we revisit the magnetic field (B-field) distribution of normal pulsars, motivated by the fact that the number of known pulsars has exceeded 3300. Here, we divided the normal pulsar samples into three subgroups by constant lines of characteristic age τ ch, i.e., young, middle-aged, and old pulsars. We note that τ ch is not used as the time indicator in this study; instead, it just served as cutting lines to divide the pulsar samples. Then, we applied several statistical tests, i.e., the Anderson-Darling, Shapiro-Wilk, Kolmogorov-Smirnov, and Mann-Whitney-Wilcoxon tests, to the selected normal pulsar samples (N = 1970) and to a data set of 32 neutron stars (NSs) in high-mass X-ray binaries (HMXBs) for comparison purposes. We obtained that (i) the conclusion on the characteristic B field (B ch) log-normal distribution for the normal pulsars by the previous studies is no longer appropriate, while only young pulsars (N = 24, τ ch &lt; 15 kyr) follow a log-normal distribution, indicating that only the B ch of young pulsars is close to real B fields. (ii) In the directly measured B-field range of NS-HMXBs (~1012-1013 G), the B ch of young pulsars (N = 15) and the real B fields of NS-HMXBs (N = 32) are inferred to be log-normal, and they are further verified to come from the same distribution, implying that there is no significant decay for real B fields, at least within the timescale of ~10 Myr for normal pulsars. (iii) Statistically, young pulsars (N = 24) are inferred to be self-contained, suggesting that the initial spin period of pulsars is less than 515 ms. (iv) The B ch distributions of three normal pulsar subsamples are different, hinting at the existence of multiple origins for NSs.

Keywords: Neutron stars, X-ray binary stars, Pulsars, Magnetic fields, Astrostatistics strategies
Photometric and Spectroscopic Studies of the Long-Period Low-Mass-Ratio Deep-Contact Binary KN Per. Photometric analysis and spectroscopic study of the long-period low-mass-ratio deep-contact binary KN Per were performed. The light curves of the BV(RI) c  band were from the Ningbo Bureau of Education and Xinjiang Observatory Telescope at the Xingming Observatory. Through the analysis of the Wilson-Devinney program, KN Per was found as an A-type low-mass-ratio deep-contact binary (q = 0.236; f = 53.4%). A cool spot applied on the primary component was introduced to explain the unequal maxima of the light curve. Based on the O - C analysis, we found that the rate of the increasing orbital period is $\dot{P}$ = 5.12 ± (0.30) × 10-7 day yr-1, meaning the mass transfer from the secondary component to the primary one. By analyzing the spectroscopic data, we detected chromospheric activity emission line indicators, which correspond to the light-curve analysis. Seventy-one long-period (P &gt; 0.5 day) contact binaries, including our target, were collected. The evolutionary states of all collected stars were investigated by the illustrations of mass-radius, mass-luminosity, and log M  T -log J  o . The relations of some physical parameters were also determined. With the instability parameters of KN Per, we determined that it is a stable contact binary system at present.

Keywords: Eclipsing binary stars, Magnetic stars, Binary stars, Contact binary stars
CASA, the Common Astronomy Software Applications for Radio Astronomy. CASA, the Common Astronomy Software Applications, is the primary data processing software for the Atacama Large Millimeter/submillimeter Array (ALMA) and the Karl G. Jansky Very Large Array (VLA), and is frequently used also for other radio telescopes. The CASA software can handle data from single-dish, aperture-synthesis, and Very Long Baseline Interferometery (VLBI) telescopes. One of its core functionalities is to support the calibration and imaging pipelines for ALMA, VLA, VLA Sky Survey, and the Nobeyama 45 m telescope. This paper presents a high-level overview of the basic structure of the CASA software, as well as procedures for calibrating and imaging astronomical radio data in CASA. CASA is being developed by an international consortium of scientists and software engineers based at the National Radio Astronomy Observatory (NRAO), the European Southern Observatory, the National Astronomical Observatory of Japan, and the Joint Institute for VLBI European Research Infrastructure Consortium (JIV-ERIC), under the guidance of NRAO.

Keywords: Software documentation, Open source software, Aperture synthesis, Astronomy software, Astronomy data analysis, Long baseline interferometry, Single-dish antennas, Radio interferometry, Radio astronomy, Astronomy data reduction
A Self-learning Neural Network Approach for Radio Frequency Interference Detection and Removal in Radio Astronomy. We present a novel neural network (NN) method for the detection and removal of radio frequency interference (RFI) from the raw digitized signal in the signal processing chain of a typical radio astronomy experiment. The main advantage of our method is that it does not require a training set. Instead, our method relies on the fact that the true signal of interest coming from astronomical sources is thermal and therefore described as a Gaussian random process, which cannot be compressed. We employ a variational encoder/decoder network to find the compressible information in the data stream that can explain the most variance with the fewest degrees of freedom. We demonstrate it on a set of toy problems and stored ring buffers from the Baryon Mapping eXperiment prototype. We find that the RFI subtraction is effective at cleaning simulated time streams: While we find that the power spectra of the RFI-cleaned time streams output by the NN suffer from extra signal consistent with additive noise, we find that it is generally around percent level across the band and sub 10% in contaminated spectral channels even when RFI power is an order of magnitude larger than the signal. We discuss the advantages and limitations of this method and possible implementation in the front end of future radio experiments.

Keywords: Neural networks, Radio telescopes, Radio interferometry, Radio astronomy, Baryon acoustic oscillations
MUPHOTEN: A MUlti-band PHOtometry Tool for TElescope Network. The early and complete temporal characterization of optical, fast, transient sources requires continuous and multiband observations over different timescales (hours to months). For time-domain astronomy, using several telescopes to analyze single objects is the usual method, allowing the acquisition of highly sampled light curves. Taking a series of images each night helps to construct an uninterrupted chain of observations with a high cadence and low duty cycle. Speed is paramount, especially at early times, in order to capture early features in the light curve that help determine the nature of the observed transients and assess their astrophysical properties. However, the problem of rapidly extracting source properties (temporal and color evolution) with a heterogeneous data set remains. Consequently, we present Muphoten, a general and fast-computation photometric pipeline able to address these constraints. It is suitable for extracting transient brightness over multitelescope and multiband networks to create a single homogeneous photometric time series. We show the performance of Muphoten with observations of the optical transient SN 2018cow (from 2018 June to 2018 July), monitored by the GRANDMA network and with the publicly available data of the Liverpool Telescope.

Keywords: Extragalactic astronomy, Astronomy data analysis, Photometry
Coherent Time-domain Canceling of Interference for Radio Astronomy. Radio astronomy is vulnerable to interference from a variety of anthropogenic sources. Among the many strategies for mitigation of this interference is coherent time-domain canceling (CTC), which ideally allows one to "look through" interference, as opposed to avoiding the interference or deleting the afflicted data. However, CTC is difficult to implement, not well understood, and at present this strategy is not in regular use at any major radio telescope. This paper presents a review of CTC including a new comprehensive study of the capabilities and limitations of CTC using metrics relevant to radio astronomy, including fraction of interference power removed and increase in noise. This work is motivated by the emergence of a new generation of communications systems which pose a significantly increased threat to radio astronomy and which may overwhelm mitigation methods now in place.

Keywords: Radio telescopes, Astronomical instrumentation, Astronomy data analysis
The Autonomous Data Reduction Pipeline for the Cute Mission. The Colorado Ultraviolet Transit Experiment (CUTE) is a 6U NASA CubeSat carrying on-board a low-resolution, near-ultraviolet (2479-3306 Å) spectrograph. It has a Cassegrain telescope with a rectangular primary to maximize the collecting area, given the shape of the satellite bus, and an aberration correcting grating to improve the image quality, and thus spectral resolution. CUTE, launched on the of 2021 September 27th to a Low Earth Orbit, is designed to monitor transiting extra-solar planets orbiting bright, nearby stars to improve our understanding of planet atmospheric escape and star-planet interaction processes. We present here the CUTE autONomous daTa ReductiOn pipeLine, developed for reducing CUTE data. The pipeline has been structured with a modular approach, which also considers scalability and adaptability to other missions carrying on-board a long-slit spectrograph. The CUTE data simulator has been used to generate synthetic observations used for developing and testing the pipeline functionalities. The pipeline has been tested and updated employing flight data obtained during commissioning and initial science operations of the mission.

Keywords: Ultraviolet astronomy, Exoplanets, Space telescopes, Astronomy software
A New Period Determination Method for Periodic Variable Stars. Variable stars play a key role in understanding the Milky Way and the universe. The era of astronomical big data presents new challenges for quick identification of interesting and important variable stars. Accurately estimating the periods is the most important step to distinguish different types of variable stars. Here, we propose a new method of determining the variability periods. By combining the statistical parameters of the light curves, the colors of the variables, the window function and the Generalized Lomb-Scargle (GLS) algorithm, the aperiodic variables are excluded and the periodic variables are divided into eclipsing binaries and NEB variables (other types of periodic variable stars other than eclipsing binaries), the periods of the two main types of variables are derived. We construct a random forest classifier based on 241,154 periodic variables from the ASAS-SN and OGLE data sets of variables. The random forest classifier is trained on 17 features, among which 11 are extracted from the light curves and 6 are from the Gaia Early DR3, ALLWISE, and 2MASS catalogs. The variables are classified into 7 superclasses and 17 subclasses. In comparison with the ASAS-SN and OGLE catalogs, the classification accuracy is generally above approximately 82% and the period accuracy is 70%-99%. To further test the reliability of the new method and classifier, we compare our results with the results of Chen et al. for ZTF DR2. The classification accuracy is generally above 70%. The period accuracy of the EW and SR variables is ~50% and 53%, respectively. And the period accuracy of other types of variables is 65%-98%.

Keywords: Period determination, Periodic variable stars, Light curve classification