A Catalog Of Ultraviolet Variables Observed By GALEX With Sub-Minute Resolution ("GFCAT")

GFCAT is the result of a systematic search for intra-visit variability using calibrated GALEX photon events to construct lightcurves at 30-second time resolution. Using the gPhoton2 software package, a semi-automated search for variable objects was conducted using calibrated photon events from every GALEX visit with at least 500 seconds of exposure time. This is equivalent to searching all visits from the Medium Image Survey ("MIS") or longer exposure lengths. Source detection was run on the resultant time series of images, and aperture photometry applied in both FUV (where available) and NUV bands using five photometric apertures. Variable objects were first identified through automated detection and then by-hand screening. The final product consists of 1959 lightcurves from 1426 unique sources. The lightcurves are constructed using five aperture sizes (9, 12.5, 17.5, 25, and 35 arcseconds), stored in separate FITS files. Each GALEX eclipse is analyzed independently, thus, variable objects observed more than once will have more than one set of lightcurves created. Four catalogs are also provided: an object catalog containing information about the unique objects, a visit catalog containing information about the vetted variable objects in each GALEX visit, an eclipse catalog containing those sources identified as looking like eclipsing objects through visual inspection, and a flare catalog containing those sources identified as looking like flares. GFCAT should not be considered suitable for general population studies or statistics: the goal was to locate as many intra-visit variables as possible in the GALEX photon database, at the expense of analyzing selection effects.