Abstract
We present the second Galaxy Evolution Explorer (GALEX) Ultraviolet Variability (GUVV-2) Catalog, which contains information on 410 newly discovered time-variable sources gained through simultaneous near UV (NUV 1750–2750 Å) and far-UV (FUV 1350–1750 Å) photometric observations. Source variability was determined by comparing the NUV and/or FUV fluxes derived from orbital exposures recorded during a series of multiple observational visits to 169 GALEX fields on the sky. These sources, which were contained within a sky area of 161 deg2, varied on average by ΔNUV = 0.6 mag and ΔFUV = 0.9 mag during these observations. Of the 114 variable sources in the catalog with previously known identifications, ∼67% can be categorized as being active galaxies (quasar stellar objects (QSOs), Seyfert 1, or BL Lac objects). The next largest groups of UV variables are RR Lyrae stars, X-ray sources, and novae. By using a combination of UV and visible color–color plots we have been able to tentatively identify 36 possible RR Lyrae- and/or δ Scuti-type stars, as well as 35 probable active galactic nuclei (AGNs), many of which may be previously unidentified QSOs or blazars. Finally, we show data for three particular variable objects: the contact binary system of Sloan Digital Sky Survey (SDSS) J141818.97+525006.7, the eclipsing dwarf nova system of IY UMa and the highly variable unidentified source SDSS J104325.06+563258.1.
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