Catalog of SDSS Quasar Absorption Redshifts Measured from Mg II Absorption Lines. I. For Sources with z em ≤ 0.8

Abstract

Abstract We are going to analyze the whole Sloan Digital Sky Survey (SDSS) quasar spectra by visually identifying Mg II absorption line systems one by one. In this paper, we limit our analysis to quasars with $ z_{\rm em}$$ \leq$ 0.8, which leaves 8006 quasars in total. Based on this, we are able to present the first catalog of these redshifts (in the interval of 0.36 $ <$$ z_{\rm abs}$$ <$ 0.81) in our series work (an analysis of higher redshift quasars will be performed later). Our work is based on spectral data previously analyzed by Quider et al. (2011, AJ, 141, 137). These authors identified Mg II absorption-line systems mainly based on search by machine; they found only 394 Mg II absorption lines from these 8006 quasars. However, for the same sample, we identified 4158 Mg II quasar absorption line systems. In our catalog, about 81% (3353/4158) of the absorbers have $ W_{\rm r}\lambda$ 2796 $ \ge$ 0.3 Å, and about 71% (2957/4158) of the absorbers have $ W_{\rm r}\lambda$ 2803 $ \ge$ 0.3 Å, showing that the main portion of our catalog is likely to be occupied by strong absorbers.