A Catalog of Spectroscopically Confirmed White Dwarfs from the Sloan   Digital Sky Survey Data Release 4
  We present a catalog of 9316 spectroscopically confirmed white dwarfs from the Sloan Digital Sky Survey Data Release 4. We have selected the stars through photometric cuts and spectroscopic modeling, backed up by a set of visual inspections. Roughly 6000 of the stars are new discoveries, roughly doubling the number of spectroscopically confirmed white dwarfs. We analyze the stars by performing temperature and surface gravity fits to grids of pure hydrogen and helium atmospheres. Among the rare outliers are a set of presumed helium-core DA white dwarfs with estimated masses below 0.3 Msun, including two candidates that may be the lowest masses yet found. We also present a list of 928 hot subdwarfs. 
Daniel J. Eisenstein, James Liebert, Hugh C. Harris, S.J. Kleinmann,   Atsuko Nitta, Nicole Silvestri, Scott A. Anderson, J....