SDSS DR7 White Dwarf Catalog
  We present a new catalog of spectroscopically-confirmed white dwarf stars
from the Sloan Digital Sky Survey Data Release 7 spectroscopic catalog. We find
20,407 white dwarf spectra, representing 19,712 stars, and provide atmospheric
model fits to 14,120 DA and 1011 DB white dwarf spectra from 12,843 and 923
stars, respectively. These numbers represent a more than factor of two increase
in the total number of white dwarf stars from the previous SDSS white dwarf
catalog based on DR4 data. Our distribution of subtypes varies from previous
catalogs due to our more conservative, manual classifications of each star in
our catalog, supplementing our automatic fits. In particular, we find a large
number of magnetic white dwarf stars whose small Zeeman splittings mimic
increased Stark broadening that would otherwise result in an overestimated
log(g) if fit as a non-magnetic white dwarf. We calculate mean DA and DB masses
for our clean, non-magnetic sample and find the DB mean mass is statistically
larger than that for the DAs.
