The Second Galex Ultraviolet Variability (GUVV-2) Catalog

TL;DR

This paper introduces the GUVV-2 catalog, listing 410 ultraviolet variable sources observed by GALEX, including active galaxies, stars, and other objects, with analysis of their variability and potential classifications.

Contribution

The GUVV-2 catalog is the second release providing detailed UV variability data for 410 sources, including new potential identifications of RR Lyrae stars and AGN.

Findings

410 UV variable sources cataloged

67 active galaxies identified among variables

36 potential RR Lyrae/Delta Scuti stars and 35 probable AGN

Abstract

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 1350-1750A) ultraviolet 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 square deg, varied on average by amplitudes of NUV = 0.6 mag and FUV = 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 (QSO's, 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 Delta Scuti type stars, as well as 35 probable AGN's, many of which may be previously unidentified QSO's or blazars. Finally, we show data for 3 particular variable objects: the contact binary system of SDSS J141818.97+525006.7, the eclipsing dwarf nova system of IY UMa and the highly variable unidentified source SDSS J104325.06+563258.1.