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We present the second Galaxy Evolution Explorer (GALEX) Ultraviolet Variability (GUVV-2) Catalog that contains information on 410 newly discovered time-variable sources gained through simultaneous near (NUV 1750-2750A) and far (FUV…

Astrophysics · Physics 2009-11-13 Jonathan M. Wheatley , Barry Y. Welsh , Stanley E. Browne

We present Version 1.0 of the NASA Galaxy Evolution Explorer (GALEX) ultraviolet variability catalog (GUVV) that contains information on 84 time-variable and transient sources gained with simultaneous near and far ultraviolet photometric…

We search for photometric variability in more than 23,000 known and candidate white dwarfs, the largest ultraviolet survey compiled for a single study of white dwarfs. We use gPhoton, a publicly available calibration/reduction pipeline, to…

Solar and Stellar Astrophysics · Physics 2019-05-01 Dominick M. Rowan , Michael A. Tucker , Benjamin J. Shappee , J. J. Hermes

Using three epochs of VLA observations of the Galactic Plane in the first quadrant taken ~15 years apart, we have conducted a search for a population of variable Galactic radio emitters in the flux density range 1-100 mJy at 6 cm. We find…

Astrophysics of Galaxies · Physics 2015-05-18 Robert H. Becker , David J. Helfand , Richard L. White , Deanne D. Proctor

Using archival observations recorded over a 5+ year timeframe with the NASA Galaxy Evolution Explorer (GALEX) satellite, we present a study of the ultraviolet (UV) variability of 4360 quasars of redshifts up to z=2.5 that have optical…

Astrophysics of Galaxies · Physics 2015-05-27 Barry Y. Welsh , Jonathan M. Wheatley , James D. Neill

We present the selection and classification of over a thousand ultraviolet (UV) variable sources discovered in ~ 40 deg^2 of GALEX Time Domain Survey (TDS) NUV images observed with a cadence of 2 days and a baseline of observations of ~ 3…

We present comprehensive catalogs of hot star candidates in the Milky Way, selected from GALEX far-UV (FUV, 1344-1786 AA) and near-UV (NUV, 1771-2831 AA) imaging. The FUV and NUV photometry allows us to extract the hottest stellar objects,…

Solar and Stellar Astrophysics · Physics 2015-05-20 Luciana Bianchi , Boryana Efremova , James Herald , Leo Girardi , Alexandre Zabot , Paola Marigo , Christopher Martin

We present a catalog of 71,364 point-like UV sources with SDSS photometry and GALEX FUV-NUV less or equal 0.1mag. The limit corresponds to stellar Teff greater than 15,000 to 20,000K, slightly depending on gravity but nearly…

Solar and Stellar Astrophysics · Physics 2024-09-10 Luciana Bianchi

We analyse a sample of 21 active galactic nuclei (AGN) using data from the Swift satellite to study the variability properties of the population in the X-ray, UV and optical band. We find that the variable part of the UV-optical emission…

High Energy Astrophysical Phenomena · Physics 2016-11-23 Douglas J. K. Buisson , Anne M. Lohfink , William N. Alston , Andrew C. Fabian

Radio-loud active galactic nuclei (AGN) are among the most luminous objects in the Universe, emitting radiation from low-energy radio waves to high energy $\gamma$-rays. They are well known to exhibit flux variations at nearly all…

Astrophysics of Galaxies · Physics 2026-03-19 M. Reshma , C. S. Stalin , Amit Kumar Mandal , S. B. Gudennavar , Senorita Benedict , Prajwel Joseph

The stellar evolution theory of massive stars remains uncalibrated with high-precision photometric observational data mainly due to a small number of luminous stars that are monitored from space. Automated all-sky surveys have revealed…

Solar and Stellar Astrophysics · Physics 2017-02-08 Jaan Laur , Indrek Kolka , Tõnis Eenmäe , Taavi Tuvikene , Laurits Leedjärv

Discovery and characterisation of black holes (BHs), neutron stars (NSs), and white dwarfs (WDs) with detached luminous companions (LCs) in wide orbits are exciting because they are important test beds for dark remnant (DR) formation…

Solar and Stellar Astrophysics · Physics 2023-07-12 Anindya Ganguly , Prasanta K. Nayak , Sourav Chatterjee

We present results from a search for short time-scale white dwarf variability using \texttt{gPhoton}, a time-tagged database of \textit{GALEX} photon events and associated software package. We conducted a survey of $320$ white dwarf stars…

We present a collection of 10 111 genuine delta Sct-type pulsating variable stars detected in the OGLE-IV Galactic bulge fields. In this sample, 9835 variables are new discoveries. For most of the stars photometric data cover the whole…

We present the first catalogue of point-source UV-excess sources selected from the UVEX survey. UVEX images the Northern Galactic Plane in the U, g, r and HeI5875 bands in the Galactic latitude range -5deg<b<+5deg. Through an automated…

We have performed the first systematic search of the full GALEX data archive for astrophysical variability on timescales of seconds to minutes by rebinning data across the whole mission to 30-second time resolution. The result is the GALEX…

Solar and Stellar Astrophysics · Physics 2023-06-29 Chase C. Million , Michael St. Clair , Scott W. Fleming , Luciana Bianchi , Rachel Osten

Most of the sources detected in the extreme ultraviolet (EUV; 100 Ang to 600 Ang) by the Rosat WFC and EUVE all-sky surveys have been identified with active late-type stars and hot white dwarfs that are near enough to escape absorption by…

Astrophysics · Physics 2015-06-24 Dan Maoz , Eran Ofek , Amotz Shemi

We present the results of a 2-epoch variability survey in the Hubble Deep Field with the goal of investigating the population of AGN to z=1. The primary data sets analyzed for galactic variability are the original HDF observations obtained…

Astrophysics · Physics 2009-11-10 Vicki L. Sarajedini , Ronald L. Gilliland , Christina Kasm

The Gaia mission has observed over 2 billion stars repeatedly across the entire sky over 10 years, revealing the many astronomical objects that vary on human timescales from seconds to years. Its repeated astrometric, photometric,…

Instrumentation and Methods for Astrophysics · Physics 2025-11-04 L. Eyer , P. Huijse , N. Chornay , J. De Ridder , B. Holl , L. Rimoldini , K. Nienartowicz , G. Jevardat de Fombelle

We have performed a comprehensive search of a VISTA Variables in the Via Lactea (VVV) database of 9.5 yr light curves for variable sources with $\Delta K_s \ge 4$ mag, aiming to provide a large sample of high amplitude eruptive young…

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