The Sloan Digital Sky Survey quasar catalog: ninth data rele ase

We present the Data Release 9 Quasar (DR9Q) catalog from the B aryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey III. The catalog includes all BOSS objects that were targete d as quasar candidates during the survey, are spectrocopica lly confirmed as quasars via visual inspection, have luminosities Mi [z=2] < −20.5 (in aΛCDM cosmology withH0 = 70 km s−1 Mpc−1, ΩM = 0.3, andΩΛ = 0.7) and either display at least one emission line with full width at half max imum (FWHM) larger than 500 km s −1 or, if not, have interesting /complex absorption features. It includes as well, known quasars (mostly from SD S -I and II) that were reobserved by BOSS. This catalog conta ins 87,822 quasars (78,086 are new discoveries) detected over 3,275 deg 2 with robust identification and redshift measured by a combin atio of principal component eigenspectra newly derived from a training set of 8,632 spec tra from SDSS-DR7. The number of quasars with z > 2.15 (61,931) is∼2.8 times larger than the number of z > 2.15 quasars previously known. Redshifts and FWHMs are provid ed for the strongest emission lines (C iv, C iii], Mg ii). The catalog identifies 7,533 broad absorption line quasar s and gives their characteristics. For each object the catal og presents five-band (u, g, r, i, z) CCD-based photometry with typical accuracy of 0.03 mag, an d information on the morphology and selection method. The ca talog also contains X-ray, ultraviolet, near-infrared, and radi o emission properties of the quasars, when available, from o ther large-area surveys. The calibrated digital spectra cover the wavelength region 3,6 00-10,500 Å at a spectral resolution in the range 1,300 < R < 2,500; the spectra can be retrieved from the SDSS Catalog Archive Server. We also prov ide a supplemental list of an additional 949 quasars that hav e been identified, among galaxy targets of the BOSS or among quasar targets after DR9 w as frozen.