High X-Ray-to-Optical Flux Ratio Sources From RASS

We present the first results of a program to identify the unknown bright active galactic nuclei (AGN)in the ROSAT All Sky Survey Bright Source Catalog (RASSBSC).We have used lgC+04 R as an alternative expression for lg(f_xf_opt), where C is X-ray count rate and R stands for R magnitude.Then a high X-ray-to-optical flux ratio criterion has been used to select an AGN sample with 165 unidentified X-ray sources fo roptical spect roscopy.At present over 93% of the X-ray sources in the sample have been fully identified in the following classes:emission line AGNs, clusters of galaxies, BLLacertae objects, and stars.