Expectations for X-ray cluster observations by the Rosat satellite

Predictions for characteristics of the X-ray cluster population expected to be observed by the Rosat satellite are presented via theoretical models for the evolution of X-ray cluster abundances. With a square detect cell of side 4.8 arcmin employed to search for extended cluster sources, roughly 200 clusters per steradian above the all-sky survey limiting flux of 7 x 10 exp -13 ergs/s sq cm are expected. For the north ecliptic pole region of the Rosat survey, which is to cover a 10-deg radius field to a limiting flux of roughly 9 x 10 exp -14 ergs/s sq cm, about 330 cluster X-ray sources are predicted. The clusters should have a median redshift of 0.2, and 10 percent of them should have z greater than 0.4.