EINSTEIN X-RAY OBSERVATIONS OF THE CORE OF THE SHAPLEY SUPERCLUSTER IN NORTHERN CENTAURUS

We present Einstein X-ray observations of the core of the Shapley Supe rcluster, one of the richest and densest known mass concentrations in the local (z < 0.1) universe. We used Imaging Proportional Counter (IP C) observations supplemented with data from the Einstein Slew Survey t o determine the locations and structure of mass concentrations in the region. An X-ray map composed of IPC observations of the central (10-d egrees x 10-degrees) region of the Shapley Supercluster is presented. We present evidence that the X-ray clusters observed within 5-degrees of the core of the supercluster are on average brighter than those of corresponding richness class distributed throughout the sky. However, we measure no significant difference in the galaxy formation efficienc y of these clusters of galaxies compared to other, more isolated clust ers. We also find one previously uncataloged cluster-sized mass concen tration in the core of the Shapley Supercluster. This new cluster, ''S C 1327 - 312'', is relatively X-ray bright (F(x) = 1.1 +/- 0.2 x 10(-1 1) erg s-1 cm-2 and L(x) = 1.1 +/- 0.2 x 10(44) ergs s-1 within 10', a ssuming z = 0.0477, H-0 = 50, q0 = 0). As SC 1327-312 lies well within an Abell radius of the richness R = 4 cluster Shapley 8 (A3558), we s uggest it may contribute to an artificially high galaxy count and rich ness classification for Shapley 8. From slew data, we estimate an X-ra y luminosity for Shapley 8 which is just half the mean luminosity of t he four other R = 4 clusters observed by the IPC, further suggesting t he richness classification to be an overestimate.