The Hamburg/RASS Catalogue of optical identifications

Abstract

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 Hamburg Quasar Survey (HQS). The plates enable an effective selection of several X-ray emitting classes of objects, as there are galaxies, AGN, QSOs, galaxy clusters and several types of galactic stars, in particular M dwarfs, hot white dwarfs and cataclysmic variables. In the current state (November 1996) the HRC contains information about 3847 X-ray positions and covers about 8480 deg2 of the high galactic latitude |b| > 20°) northern sky. For 81.2% of the X-ray sources a plausible optical counterpart is given. The counterparts of the remaining sources are probably faint (B > 18.5) AGN and galaxy clusters. The HRC is available electronically together with finding charts taken from the digitized direct HQS plates.