Searching for X-ray Galaxy Clusters in the Zone of Avoidance

Based on the ROSAT All-Sky Survey we are constructing a sample of the X-ray brightest galaxy clusters for cosmological studies. We have already completed the compilation of a sample of about 1000 clusters in the sky excluding a 40 degree wide band around the galactic plane. We have demonstrated with the southern sample, which is the so far most complete, that we can get reliable statistical measures of the large-scale structure of the Universe to scales in excess of 400 Mpc (for Ho=100). With the experience gained in these projects we are extending the search for X-ray galaxy clusters into the Zone-of-Avoidance. We have compiled a sample of 181 good cluster candidates with a well defined completeness of about 70% down to a flux limit of 3 10e-12 erg/s/cm**2 in the zone with an absorption depth less than Av = 2.25. The candidates are definitely identified and redshifts are obtained in an ongoing optical follow-up program.