THE HAMBURG RASS CATALOG OF OPTICAL IDENTIFICATIONS/

We present the Hamburg/RASS Catalogue of optical identifications (HRC) . The catalogue contains optical information about objects inside the error circles of ROSAT All-Sky Survey (RASS) sources. The information was gathered from objective prism and direct plates taken by the Hambu rg Quasar Survey (HQS). The plates enable an effective selection of se veral X-ray emitting classes of objects, as there are galaxies, AGN, Q SOs, galaxy clusters and several types of galactic stars, in particula r M dwarfs, hot white dwarfs and cataclysmic variables. In the current state (November 1996) the HRC contains information about 3847 X-ray p ositions and covers about 8480 deg(2) of the high galactic latitude (\ b\ > 20 degrees) northern sky. For 81.2% of the X-ray sources a plausi ble optical counterpart is given. The counterparts of the remaining so urces are probably faint (B > 18.5) AGN and galaxy clusters. The HRC i s available electronically together with finding charts taken from the digitized direct HQS plates.