Statistical Properties of Bright Galaxies in the Sloan Digital Sky Survey Photometric System

We investigate the photometric properties of 456 bright galaxies usingimaging data recorded during the commissioning phase of the Sloan Digital SkySurvey (SDSS). Morphological classification is carried out by correlatingresults of several human classifiers. Our purpose is to examine the statisticalproperties of color indices, scale lengths, and concentration indices asfunctions of morphology for the SDSS photometric system. We find that $u'-g'$,$g'-r'$, and $r'-i'$ colors of SDSS galaxies match well with those expectedfrom the synthetic calculation of spectroscopic energy distribution of templategalaxies and with those transformed from $UBVR_CI_C$ color data of nearbygalaxies. The agreement is somewhat poor, however, for $i'-z'$ color band witha discrepancy of $0.1-0.2$ mag. With the aid of the relation between surfacebrightness and radius obtained by Kent (1985), we estimate the averages of theeffective radius of early type galaxies and the scale length of exponentialdisks both to be 2.6 kpc for $L^*$ galaxies. We find that the half light radiusof galaxies depends slightly on the color bands, consistent with the expecteddistribution of star-forming regions for late type galaxies and with the knowncolor gradient for early type galaxies. We also show that the (inverse)concentration index, defined by the ratio of the half light Petrosian radius tothe 90% light Petrosian radius, correlates tightly with the morphological type;this index allows us to classify galaxies into early (E/S0) and late (spiraland irregular) types, allowing for a 15-20% contamination from the oppositeclass compared with eye-classified morphology.Comment: 18 pages, LaTeX (aaspp4), 16 PostScript figures. Accepted for publication in AJ (September issue