The sloan digital sky survey quasar catalog. IV. Fifth data release

We present the fourth edition of the Sloan Digital Sky Survey (SDSS) Quasar Catalog. The catalog contains 77,429 objects; this is an increase of over 30,000 entries since the previous edition. The catalog consists of the objects in the SDSS Fifth Data Release that have luminosities larger than M-i = -22.0 (in a cosmology with H-0 = 70 km s(-1) Mpc(-1), Omega(M) = 0.3, and Omega(Lambda) = 0.7), have at least one emission line with FWHM larger than 1000 km s(-1) or have interesting/complex absorption features, are fainter than i approximate to 15.0, and have highly reliable redshifts. The area covered by the catalog is approximate to 5740 deg(2). The quasar redshifts range from 0.08 to 5.41, with a median value of 1.48; the catalog includes 891 quasars at redshifts greater than 4, of which 36 are at redshifts greater than 5. Approximately half of the catalog quasars have i < 19; nearly all have i < 21. For each object the catalog presents positions accurate to better than 0.2'' rms per coordinate, five-band (ugriz) CCD-based photometry with typical accuracy of 0.03 mag, and information on the morphology and selection method. The catalog also contains basic radio, near- infrared, and X-ray emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra cover the wavelength region 3800-9200 angstrom at a spectral resolution of similar or equal to 2000; the spectra can be retrieved from the public database using the information provided in the catalog. The average SDSS colors of quasars as a function of red-shift, derived from the catalog entries, are presented in tabular form. Approximately 96% of the objects in the catalog were discovered by the SDSS.