Multiwavelength Observations of a Few Unidentified EGRET Sources

More than sixty percent of the high energy gamma-ray sources detected by EGRET are unidentified, with no firmly established counterparts at other wavebands. The nature of these sources have remained a mystery in high energy astrophysics since the first surveys of the gamma-ray sky with the COS-B satellite. Some of the unidentified EGRET sources have large error circles, and a multiwavelength approach is often needed to understand the nature of these sources. Here we present results from the analysis of archival ROSAT and ASCA X-ray data of the COS-B field 2CG 075+00 in the Galactic plane, which overlaps with two EGRET sources 3EG 2016+3657 and 3EG 2021+3716. The most likely candidate for 3EG 2016+3657 is the blazar-like radio source G74.87+1.22 (B2013+370). Optical observations with the MDM 2.4m and KPNO 2.1m telescopes, as well as archival radio data are also presented to support the identification. In addition, work in progress on two other unidentified EGRET sources are also described.