Statistical Properties of the GALEX-SDSS Matched Source Catalogs, and Classification of the UV Sources

We use the Galaxy Evolution Explorer (GALEX) Medium and All-Sky Imaging Survey (MIS and AIS) data from the first public data release (GR1), matched to the Sloan Digital Sky Survey (SDSS) DR3 catalog, to perform source classification. The GALEX surveys provide photometry in far- and near-UV bands and the SDSS in five optical bands (u, g, r, i, z). The GR1/DR3 overlapping areas are 363 (86) deg^2 for the GALEX AIS (MIS), for sources within the 0.5° central area of the GALEX fields. Our sample covers mostly |b| > 30° Galactic latitudes. We present statistical properties of the GALEX-SDSS matched sources catalog, containing >2 × 10^6 objects detected in at least one UV band. We classify the matched sources by comparing the seven-band photometry to model colors constructed for different classes of astrophysical objects. For sources with photometric errors