The Application of Photometric Redshifts to the SDSS Early Data Release

The Early Data Release from the Sloan Digital Sky survey provides one of thelargest multicolor photometric catalogs currently available to the astronomicalcommunity. In this paper we present the first application of photometricredshifts to the $\sim 6$ million extended sources within these data (with 1.8million sources having $r' < 21$). Utilizing a range of photometric redshifttechniques, from empirical to template and hybrid techniques, we investigatethe statistical and systematic uncertainties present within the redshiftestimates for the EDR data. For $r'<21$ we find that the redshift estimatesprovide realistic redshift histograms with an rms uncertainty in thephotometric redshift relation of 0.035 at $r'<18$ and rising to 0.1 at $r'<21$.We conclude by describing how these photometric redshifts and derivedquantities, such as spectral type, restframe colors and absolute magnitudes,are stored within the SDSS database. We provide sample queries for searching onphotometric redshifts and list the current caveats and issues that should beunderstood before using these photometric redshifts in statistical analyses ofthe SDSS galaxies.Comment: 33 pages, 16 figure