Is the EGRET Source 3EG J1621+8203 the Radio Galaxy NGC 6251?

We discuss the nature of the unidentified EGRET source 3EG J1621+8203. In aneffort to identify the gamma-ray source, we have examined X-ray images of thefield from ROSAT PSPC, ROSAT HRI, and ASCA GIS. Of the several faint X-raypoint sources in the error circle of 3EG J1621+8203, most are stars or faintradio sources, unlikely to be counterparts to the EGRET source. The mostnotable object in the gamma-ray error box is the bright FR I radio galaxy NGC6251. If 3EG J1621+8203 corresponds to NGC 6251, then it would be the secondradio galaxy to be detected in high energy gamma rays, after Cen A, whichprovided the first clear evidence of the detection above 100 MeV of an AGN witha large-inclination jet. If the detection of more radio galaxies by EGRET hasbeen limited by its threshold sensitivity, there exists the excitingpossibility that new high energy gamma-ray instruments, with much highersensitivity, will detect a larger number of radio galaxies in the future.Comment: 7 pages, 6 figures. Accepted for publication in The Astrophysical Journal, August 2002 issu