  Type II quasars are the long-sought luminous analogs of type II (narrow
emission line) Seyfert galaxies, suggested by unification models of active
galactic nuclei (AGN) and postulated to account for an appreciable fraction of
the cosmic hard X-ray background. We present a sample of 291 type II AGN at
redshifts 0.3<Z<0.83 from the spectroscopic data of the Sloan Digital Sky
Survey. These objects have narrow (FWHM<2000 km/s), high equivalent width
emission lines with high-ionization line ratios. We describe the selection
procedure and discuss the optical properties of the sample. About 50% of the
objects have [OIII] \lambda_air 5007 line luminosities in the range 3\times
10^8-10^10 L_Sun, comparable to those of luminous (-27<M_B<-23) quasars; this,
along with other evidence, suggests that the objects in the luminous subsample
are type II quasars.

Astrophysics