Colors of 2625 Quasars at 0 < [ITAL][CLC]z[/CLC][/ITAL] < 5 Measured in the Sloan Digital Sky Survey Photometric System

We present an empirical investigation of the colors of quasars in the SloanDigital Sky Survey (SDSS) photometric system. The sample studied includes 2625quasars with SDSS photometry. The quasars are distributed in a 2.5 degree widestripe centered on the Celestial Equator covering $\sim529$ square degrees.Positions and SDSS magnitudes are given for the 898 quasars known prior to SDSSspectroscopic commissioning. New SDSS quasars represent an increase of over200% in the number of known quasars in this area of the sky. The ensembleaverage of the observed colors of quasars in the SDSS passbands are wellrepresented by a power-law continuum with $\alpha_{\nu} = -0.5$ ($f_{\nu}\propto \nu^{\alpha}$). However, the contributions of the $3000 {\rm \AA}$ bumpand other strong emission lines have a significant effect upon the colors. Thecolor-redshift relation exhibits considerable structure, which may be of use indetermining photometric redshifts for quasars. The range of colors can beaccounted for by a range in the optical spectral index with a distribution$\alpha_{\nu}=-0.5\pm0.65$ (95% confidence), but there is a red tail in thedistribution. This tail may be a sign of internal reddening. Finally, we showthat there is a continuum of properties between quasars and Seyfert galaxiesand we test the validity of the traditional division between the two classes ofAGN.Comment: 66 pages, 15 figures (3 color), accepted by A