160 square degree ROSAT survey

The median redshift is z_median_=0.25, and the median X-ray luminosity is L_X,median_=4.2x10^43^h_50_^2^erg/s (0.5-2.0keV). This is the largest high-redshift sample of X-ray-selected clusters published to date.

There are 73 objects at z>0.3 and 22 objects at z>0.5 drawn from a statistically complete flux-limited survey with a median object flux of 1.4x10^-13^erg/cm^2^/s. We describe the optical follow-up of these clusters with an emphasis on our spectroscopy, which has yielded 155 cluster redshifts, 110 of which are presented here for the first time. These measurements, combined with 45 from the literature and other sources, provide near-complete spectroscopic coverage for our survey.