The SDSS Photometric Catalog, Release 4

The present catalog is a subset of the data release 4 of the Sloan Digital Sky Survey (SDSS), restricted to primary and secondary photo objects (i.e. objects from PhotoPrimary of PhotoSecondary tables) and restricted to the columns described in the "Byte-by-Byte" description below. The complete SDSS data release 4 catalog is available from sdss.org/dr4/ The Sloan Digital Sky Survey (SDSS) will map in detail one-quarter of the entire sky, determining the positions and absolute brightnesses of more than 100 million celestial objects.

It will also measure the distances to more than a million galaxies and quasars. Apache Point Observatory, site of the SDSS telescopes, is operated by the Astrophysical Research Consortium (ARC). Funding for the SDSS has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Aeronautics and Space Administration, the National Science Foundation, the U.S. Department of Energy, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England.