Sazuna/UAT_keywords huggingface dataset:
Modal Noise Mitigation and Scrambling Performance of a Compound Scrambler. Fiber scrambling is integral to high-precision calibration systems for radial velocity (RV) measurements, crucial in the quest for exoplanet discovery. Coherent light sources, like laser frequency combs, often induce laser speckles, a form of modal noise, which can result in spectra calibration errors. The starlight collected in astronomical observations is often polychromatic light. This study investigates the speckle-like mode noise generated under incoherent light, identifying a clear correlation between fiber length and the intensity of this noise. Remarkably, experiments using LED illumination showed that fibers shorter than 2 m exhibit significant speckle-like noise, manifesting as distinctive ripple-like structures, a newly identified phenomenon referred to as modal patterns. Mitigation techniques, including squeezing and vibrating methods, can reduce contrast and suppress modal patterns effectively. To further enhance scrambling performance, a novel fiber scrambling approach, the compound scrambler, is proposed. This design integrates laser polishing, thermal heating, and fiber tapering techniques to enhance near-field uniformity. Utilizing a combination of non-circular and graded index fibers, the compound scrambler achieves notable improvements in scrambling gain (SG). A refined nondestructive fabrication method, leveraging the superior scrambling effect of non-circular fibers and the efficiency of adiabatic taper structures, achieves a high SG of 1064. These findings contribute to advancing high-precision spectrograph design, offering practical solutions to enhance RV measurement accuracy. The compound scrambler's integrity and modular design promise stability, longevity, and scalability, holding immense potential for astronomical instrumentation.

Keywords: Radial velocity
Reliability Improvement Strategies for Telescope Control Systems. The telescope drive control system provides essential power support for the successful execution of astronomical observations, and its reliability directly impacts the efficiency of these observations. This paper focuses on strategies for enhancing the reliability of the telescope drive control system, proposing a comprehensive and multidimensional reliability improvement solution. The study examines mechanisms for enhancing reliability from three perspectives: expected fault diagnosis, unanticipated state identification, and reliability optimization during the design phase. For each of these aspects, specific reliability enhancement solutions are proposed, including a fault diagnosis and self-healing expert system, a generic process model for unanticipated state identification, and an optimized tracking control strategy under timestamp synchronization. Furthermore, the paper demonstrates the feasibility of these solutions from the three aforementioned perspectives, providing a clear direction for the development of reliability enhancement strategies for telescopes.

Keywords: Computational methods, Astronomy data analysis, Ground telescopes, Telescopes
An Integral Field Unit for the Binospec Spectrograph. Binospec is a wide-field optical (360─1000 nm) spectrograph commissioned at the MMT 6.5 m telescope in 2017. In direct imaging mode Binospec addresses twin   (wide) by   (slit length) fields of view. We describe an optical fiber based integral field unit (IFU) that remaps a 12″ × 16″ contiguous region onto two pseudo slits, one in each Binospec channel. The IFU, commissioned in 2023, fits into the space of a standard slit mask frame and can be deployed as desired in a mixed program of slit masks, long slits, and IFU observations. The IFU fibers are illuminated by a hexagonal lenslet array with a 0 6 pitch. A separate bundle of sky fibers consists of close-packed bare fibers arranged within an 11 8 circular aperture. The 640 IFU fibers and 80 sky fibers have a core diameter of 150 μm, corresponding to 0 90. Three gratings are available, 270 lpm with R ~ 2000, 600 lpm with R ~ 5300, and 1000 lpm with R ~ 6000.

Keywords: Spectrometers
Quantitative Assessment of Dome Seeing for MUST Project. The Multiplexed Survey Telescope (MUST) project, led by Tsinghua University and located on Saishiteng Mountain in Qinghai Province, benefits from exceptional atmospheric seeing conditions. However, local dome seeing, which can be comparable to atmospheric seeing, necessitates careful management. This research, based on numerical simulations, focuses on optimizing the thermal insulation design of the spectrograph chamber at the dome base to prevent heat conduction to the dome layer, thereby mitigating dome seeing. A comprehensive multiphysics field coupling simulation was employed, integrating computational fluid dynamics (CFD), thermodynamics, and ray tracing. The CFD analysis utilizes the large eddy simulation model to perform three-dimensional transient simulations and to capture optical turbulence. Both forced and natural convection scenarios were considered in the convective heat transfer simulations, using tailored algorithms. Based on the flow and temperature field distributions, the refractive index field was derived, and gradient-index ray tracing was conducted through the optical system of MUST. The broadening of the point-spread function was used as a quantitative metric for evaluating dome seeing. This approach closely approximates real-world conditions, enhancing simulation accuracy. The results guided the optimization of the spectrograph chamber's thermal insulation design, demonstrating that implementing appropriate ventilation between the dome and spectrograph chamber can effectively block heat transfer, ensuring dome seeing remains within a reasonable range and preserving the observational capabilities of MUST.

Keywords: Astronomical seeing, Domes
Using SMC OB Field Stars and Field Binaries to Study the Origin and Evolution of Massive Star Populations. Doctoral Committee:Professor Sally Oey, ChairProfessor Fred AdamsProfessor Jan J. Eldridge, University of AucklandProfessor Lee Hartmann Professor Sally Oey, Chair Professor Fred Adams Professor Jan J. Eldridge, University of Auckland Professor Lee Hartmann

Keywords: Binary stars, Emission line stars, Massive stars, Small Magellanic Cloud, High mass x-ray binary stars, OB stars, Eclipsing binary stars, Radial velocity, Runaway stars
Bound Domains. How much energy is required to unbind baryons from the cosmological structures that originally bind them? This tutorial article explains why trying to answer this question using just a halo model can be misleading. Instead, it recommends parsing the universe into "bound domains," which are the gravitationally bound structures that ultimately become widely separated islands as the universe evolves. It explains why a bound domain's potential well was about as deep ∼1 Gyr after the Big Bang as it is now, and it outlines how future research might take advantage of a bound-domain approach to make progress on some open questions about the baryon distributions in and around galaxy groups and clusters.

Keywords: Galaxy clusters, Galactic winds, Galaxy groups, Galaxy accretion, Circumgalactic medium
The Fastest Path to Discovering the Second Electromagnetic Counterpart to a Gravitational Wave Event. The discovery of a second electromagnetic counterpart to a gravitational wave event represents a critical goal in the field of multi-messenger astronomy. In order to determine the optimal strategy for achieving this goal, we perform comprehensive simulations comparing two potential paths forward: continuing the current LIGO-Virgo-KAGRA (LVK) observing run, O4, versus temporarily shutting down the detectors for upgrades before beginning the next observing run, O5. Our simulations incorporate current O4 instrument sensitivities and duty cycles, as well as projected configurations for O5, while accounting for variables such as binary neutron star merger rates, system properties, viewing angles, dust extinction, and kilonova (KN) observables. Our results indicate that a KN discovery would occur   days (middle 50% interval) sooner in O5 compared to O4, suggesting that extending O4 would lead to faster discovery if the shutdown period between runs is &gt;4 months. Moreover, for 88% of our simulations, continuing O4 results in earlier KN discovery when compared to the expected two-year shutdown between O4 and O5. Given these findings and the critical importance of avoiding a &gt;10 yr gap between first and second electromagnetic counterpart discoveries, we suggest LVK consider extending O4 operations for as long as feasible prior to shutting down for critical upgrades.

Keywords: Neutron stars, R-process, Compact binary stars, Gravitational wave sources, Computational methods
Variability of Central Stars of Planetary Nebulae with the Zwicky Transient Facility. I. Methods, Short-timescale Variables, and the Unusual Nucleus of WeSb 1. A complete understanding of the central stars of planetary nebulae (CSPNe) remains elusive. Over the past several decades, time-series photometry of CSPNe has yielded significant results including, but not limited to, discoveries of nearly 100 binary systems, insights into pulsations and winds in young white dwarfs, and studies of stars undergoing very late thermal pulses. We have undertaken a systematic study of optical photometric variability of cataloged CSPNe, using the light curves from the Zwicky Transient Facility (ZTF). By applying appropriate variability metrics, we arrive at a list of 94 highly variable CSPN candidates. Based on the timescales of the light-curve activity, we classify the variables broadly into short- and long-timescale variables. In this first paper in this series, we focus on the former, which is the majority class comprising 83 objects. We report periods for six sources for the first time, and recover several known periodic variables. Among the aperiodic sources, most exhibit a jitter around a median flux with a stable amplitude, and a few show outbursts. We draw attention to WeSb 1, which shows a different kind of variability: prominent deep and aperiodic dips, resembling transits from a dust/debris disk. We find strong evidence for a binary nature of WeSb 1 (possibly an F-type subgiant companion). The compactness of the emission lines and inferred high electron densities make WeSb 1 a candidate for either an EGB 6-type planetary nucleus, or a symbiotic system inside an evolved planetary nebula, both of which are rare objects. To demonstrate further promise with ZTF, we report three additional newly identified periodic sources that do not appear in the list of highly variable sources. Finally, we also introduce a two-dimensional metric space defined by the von Neumann statistics and Pearson Skew and demonstrate its effectiveness in identifying unique variables of astrophysical interest, like WeSb 1. *Based in part on observations obtained with the Hobby–Eberly Telescope (HET), which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Ludwig-Maximillians-Universität München, and Georg-August Universität Göttingen. The HET is named in honor of its principal benefactors, William P. Hobby and Robert E. Eberly.

Keywords: Binary stars, Light curves, Planetary nebulae nuclei, Planetary nebulae, Debris disks
A Link Between White Dwarf Pulsars and Polars: Multiwavelength Observations of the 9.36-minute Period Variable Gaia22ayj. White dwarfs (WDs) are the most abundant compact objects, and recent surveys have suggested that over a third of WDs in accreting binaries host a strong (B ≳ 1 MG) magnetic field. However, the origin and evolution of WD magnetism remain under debate. Two WD pulsars, AR Sco and J191213.72─441045.1 (J1912), have been found, which are non-accreting binaries hosting rapidly spinning (1.97 minutes and 5.30 minutes, respectively) magnetic WDs. The WD in AR Sco is slowing down on a   yr timescale. It is believed they will eventually become polars, accreting systems in which a magnetic WD (B ≍ 10−240 MG) accretes from a Roche lobe-filling donor spinning in sync with the orbit (≳78 minutes). Here, we present multiwavelength data and analysis of Gaia22ayj, which outbursted in 2022 March. We find that Gaia22ayj is a magnetic accreting WD that is rapidly spinning down (  yr) like WD pulsars, but shows clear evidence of accretion, like polars. Strong linear polarization (40%) is detected in Gaia22ayj; such high levels have only been seen in the WD pulsar AR Sco and demonstrate the WD is magnetic. High speed photometry reveals a 9.36 minutes period accompanying a high amplitude (∼2 mag) modulation. We associate this with a WD spin or spin─orbit beat period, not an orbital period as was previously suggested. Fast (60 s) optical spectroscopy reveals a broad "hump," reminiscent of cyclotron emission in polars, between 4000 and 8000 Å. We find an X-ray luminosity of   in the 0.3─8 keV energy range, while two very large array radio campaigns resulted in a non-detection with a Fr &lt; 15.8 μJy 3σ upper limit. The shared properties of both WD pulsars and polars suggest that Gaia22ayj is a missing link between the two classes of magnetic WD binaries.

Keywords: Accretion, Binary stars, White dwarf stars, Time domain astronomy, Cataclysmic variable stars
Prospects for Systematic Planetary Nebulae Detection with the Census of the Local Universe Narrowband Survey. We investigate the efficacy of a systematic planetary nebula (PN) search in the Census of the Local Universe (CLU) narrowband (Hα) survey that covers a considerably larger sky region of above decl. −20° than most previous surveys. Using PNe observed by the Isaac Newton Telescope Photometric Hα Survey as validation, we are able to visually recover 432 out of 441 cataloged PNe (98%) within the CLU data set, with 5 sources having unusable CLU images and 4 missed due to limitations of imaging quality. Moreover, the reference PNe are conventionally divided into three PN classes in decreasing order of identification confidence given their spectra and morphologies. We record consistently high recovery rate across all classes: 95% of True, 71% of Likely, and 81% of Possible sources are readily recovered. To further demonstrate the ability of CLU to find new PNe, we undertake a preliminary search of compact PNe within a sub-region of the validation catalog, mainly utilizing the significance of narrow-band colors (Σ) as a metric for identification. In a 200 deg2 region, we search the CLU source catalog and find 31 PN candidates after automated and visual scrutiny, of which 12 are new sources not appearing in previous studies. As a demonstration of our ongoing follow-up campaign, we present medium-resolution optical spectra of six candidates and notice that four of them show emission signatures characteristic of confirmed PNe. As we refine our selection methods, CLU promises to provide a systematic catalog of PNe spanning 2/3 of the sky.

Keywords: Surveys, Planetary nebulae, H II regions, H alpha photometry
Polarization and Interstellar Extinction Towards the Open Star Cluster NGC 6633. We present optical polarization data of 110 stars in the direction of NGC 6633. From multi-wavelength BVRI measurements of 64 of these stars we obtained a wavelength of maximum polarization that yielded an estimate of total-to-selective extinction ratio RV = 3.18 ± 0.04 over the observed region. The distribution of the polarization position angles overall reveals a fairly uniform Galactic magnetic field. The fractional V-band polarization of the cluster's members is between 0.8% and 1.4%, clearly above the 0.5% average value measured for the nearby field stars in the sample. We analyze the V-band polarization and maximum polarization as a function of color excess and extinction based on dust maps, Gaia, and uvbyβ photometry to discuss the polarization efficiency. The interpretation depends on the set of color excess or extinction data used, but for the majority of stars the polarization is confined below the empirical pmax ∼ 9%E(B − V) upper limit for the maximum polarization. On average, the normalized Stokes parameters show a slight offset of the foreground and background stars in comparison to the cluster's members, but a significant overlap for many stars along the line of sight is present. We discuss a comparison of our optical polarization measurements to the Planck data in the context of the interpretation that the dust causing the infrared emission is also responsible for the optical polarization. We suggest that the polarization we measure for stars at the cluster's distance around 400 pc is due to foreground dust between 100 and 350 pc and that multiple clouds along the line of sight could be the reason for some of the variations we observe.

Keywords: Starlight polarization, Interstellar dust extinction, Star clusters
Search Capability for Near-Earth Objects with the Wide Field Survey Telescope. Wide Field Survey Telescope (WFST), with a powerful sky survey capability in the northern hemisphere, will play an important role in asteroid searching and monitoring. However, WFST is not a telescope dedicated to near-Earth asteroids (NEOs) searching. In order to improve the efficiency of finding NEOs on the premise of meeting the needs of other scientific research, we ran mock observations for WFST to study its search capability for NEOs. The NEO population model, the WFST detection model and site conditions are taken into account in our simulations. Based on the original scheduling scheme, we present two new schemes. Compared to the original scheme, the optimized scheme can improve the search capability of known and unknown NEOs by 100% and 50%. We also emphasized the importance of trailing loss and proposed an improved effective field of view model. In addition, it is predicted that adopting the clear-day ratio of 0.7 and the optimized scheme, during one year of regular survey, for NEOs with absolute magnitude from 17 to 25, WFST can provide tracklets for about 1800 NEOs if their orbits are known, and in the case of blind search, more than 600 NEOs can be found by WFST. The new schemes provide valuable reference and suggestions for the WFST's regular survey strategy.

Keywords: Near-Earth objects, Asteroids, Sky surveys, Small Solar System bodies
The T16 Project: Image Subtraction Light Curves from TESS Cycle 1 Full-frame Images for Stars with T &lt; 16. We present 83,717,159 light curves for 56,401,549 stars with T &lt; 16 mag observed in the Full-Frame Images (FFIs) of Cycle 1 of the NASA TESS mission. These light curves were extracted from subtracted images produced by the Cluster Difference Imaging Survey. We make public the raw image subtraction light curves, together with light curves de-trended against instrumental systematics. We compare the light curves to other publicly available light curves from the TESS FFIs, finding that for a substantial fraction of stars with T &lt; 16, the T16 project provides the highest precision FFI light curves available. We demonstrate that the detrended T16 light curves are generally as good as, or better than, than the light curves from other projects for the known TOIs. We also show that the un-detrended light curves can be used to study high amplitude variable stars. The light curves are being made available through the NASA Mikulski Archive for Space Telescopes. Light curve production is underway for additional TESS Cycles.

Keywords: Light curves, Photometry
A L<SUB>q</SUB> Proximal Gradient Algorithm for Radio-interferometric Imaging. The reconstruction from the measured visibilities to the signal in radio interferometry is an ill-posed inverse problem. The compressed sensing technology represented by the sparsity averaging reweighted analysis (SARA) has been successfully applied to radio-interferometric imaging. However, the traditional SARA algorithm solves the L1 norm minimization problem instead of the L0 norm one, which has a bias problem. In this paper, a Lq proximal gradient algorithm with 0 &lt; q &lt; 1 is proposed to ameliorate the bias problem and obtain an accurate solution in radio interferometry. The proposed method efficiently solves the Lq norm minimization problem by using the proximal gradient algorithm, and adopts restart and lazy-start strategies to reduce oscillations and accelerate the convergence rate. Numerical experiment results and quantitative analyses verify the effectiveness of the proposed method.

Keywords: Radio interferometry, Radio telescopes, Interferometers
A Flexible Spherical Mixture Model for Gamma-Ray Burst Patterns Obtained from BATSE and FERMI Mission. The study encapsulates the investigation into the spherical distributional characteristics of parameters relevant to Gamma-Ray Bursts (GRBs), mainly focusing on their Galactic coordinates. The study utilized a mixture of von Mises Fisher spherical distributions to model the spatial distribution of GRBs in both BATSE and FERMI catalogs. Optimal numbers of mixture components were determined for different subsets of GRBs, including Long and Short GRBs. For the BATSE catalog, it turns out that a mixture of two spherical distributions provides a good fit for the whole data set and long and short GRBs. On the other hand, for the FERMI catalog, it turns out that a mixture of three spherical distributions provides a good fit for the whole data set, and a mixture of four distributions is adequate for both long and short GRBs. Additionally, an assessment was made to determine if the location parameter of GRBs follows any spherical distribution. Our flexible directional statistical modeling framework reveals that GRBs exhibit a non-uniform distribution on the celestial sphere, as evidenced by rejecting the null hypothesis of uniform distribution on a sphere using the Watson test. Our analysis statistically inquires the long-held assumption of their isotropic spread, especially in 2D projected spatial distributions of GRBs, suggesting that these cosmic events might not be uniformly scattered across the celestial sphere. The observed clumping of GRBs hints at the underlying cosmic scaffolding—the large-scale distribution of matter and star formation. Our results statistically asserts the explanation that the intrinsic GRB formation rate is typically tied to cosmic star formation rates with a delay time distribution, leading to a non-uniform rate as a function of redshift, demanding more nuanced calculations. However, this finding needs to consider potential biases introduced by the Milky Way's obscuration and our heliocentric perspective.

Keywords: Astrostatistics distributions, Gamma-ray bursters, Astronomy data analysis, Astrostatistics