Classification and Characterization of Objects from the Galaxy Evolution Explorer Survey and the Sloan Digital Sky Survey

Abstract

We use the Galaxy Evolution Explorer (GALEX) Medium Imaging Survey (MIS) and All-sky Imaging Survey (AIS) data available in the first internal release, matched to the Sloan Digital Sky Survey (SDSS) catalogs in the overlapping regions, to classify objects by comparing the multiband photometry to model colors. We show an example of the advantage of such broad wavelength coverage (GALEX far-UV and near-UV, SDSS ugriz) in classifying objects and augmenting the existing samples and catalogs. From the MIS (AIS) sample over an area of 75 (92) deg2, we select a total of 1736 (222) QSO candidates at redshifts less than 2, significantly extending the number of fainter candidates and moderately increasing the number of bright objects in the SDSS list of spectroscopically confirmed QSOs. Numerous hot stellar objects are also revealed by the UV colors, as expected.