Identification of a complete sample of northern ROSAT All-Sky Survey X-ray sources

F.-J. Zickgraf, I. Thiering, J. Krautter, I. Appenzeller, R. Kneer, W. H. Voges, B. Ziegler, C. Chavarria, A. Serrano, R. Mujica, M. Pakull, J. Heidt
1997 Astronomy and Astrophysics Supplement Series  
We describe a program for the optical identification of a representative sample of RASS sources contained in six study areas north of δ = −9 • , with |b II | > ∼ 20 • including one region near the North Galactic pole (NGP) and one near the North 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 "extragalactic" ( e.g. AGN, clusters of galaxies) to "stellar"
more » ... (e.g. coronal emitters, active binaries) counterparts was found to depend on the galactic 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 counterparts.
doi:10.1051/aas:1997347 fatcat:i6hqpqcjnfcczh4khkqeiql7hi