IDENTIFICATION OF A COMPLETE SAMPLE OF NORTHERN ROSAT ALL-SKY SURVEY X-RAY SOURCES .2. THE OPTICAL OBSERVATIONS

We describe a program for the optical identification of a representati ve sample of RASS sources contained in six study areas north of delta = -9 degrees, with \b(II)\ greater than or similar to 20 degrees inclu ding one region near the North Galactic pole ((NGP) and one near the N orth Ecliptic pole (NEP) and present some preliminary results. A full identification has been carried out for a count-rate and area-limited complete subsample comprising 674 sources. The ratio of ''extragalacti c'' ( e.g. AGN, clusters of galaxies) to ''stellar'' (e.g. coronal emi tters, active binaries) counterparts was found to depend on the galact ic neutral hydrogen column density, N-H. In the area near the NGP (low N-H) ''extragalactic'' counterparts dominate, while in the area with the highest N-H most X-ray sources are identified with stellar counter parts.