ROSAT PSPC OBSERVATIONS OF THE RICHEST (R> = 2 ) ACO CLUSTERS

摘要

We have compiled an X-ray catalog of optically selected rich clusters of galaxies observed by the Posi- tion Sensitive Proportional Counter (PSPC) during the pointed GO phase of the ROSAT mission. This paper contains a systematic X-ray analysis of l50 dusters with an optical richness classification of R > = 2 from the Abell, Corwin, & Olowin (ACO) catalog. All clusters were observed within 45 ' of the optical axis of the telescope during pointed PSPC observations. For each cluster, we calculate: the net 0.5--2.0 kev PSPC count rate in a 1 MPC radius aperture, o.5--2.o kev nux and luminosity, bolometric luminosity, and X-ray centroid. The cluster sample is then used to examine correlations between the X-ray and optical properties of clusters, derive the X-ray lumininosity function of clusters with' different optical classifications, and obtain a quantitative estimate of contamination (i.e., the fraction of clusters with an optical richness significantly overestimated due to interloping galaxies) in the ACO catalog. Because of the large field of view of the PSPC, many rich clusters were serendipitously observed during the GO phase of the ROSAT mission, Of the 150 clusters in our sample, 82 were observed seren- dipitously and 68 were targeted observations. The overall detection rate of serendipitously observed clus- ters is quite high at 76. However, the detection rate is sensitive to the optical properties of clusters, and the details of the optical selection process. For example, all serendipitously observed Bautz-Morgan type I and type III clusters are detected, while onl