Multiwavelength Examination of the COS – B Field 2 CG 075 + 00 Yields a Blazar Identification for 3 EG J 2016 + 3657

Accepted by The Astrophysical Journal Received ; accepted – 2 – ABSTRACT We present a high-energy study of the intriguing COS–B γ-ray field, 2CG 075+00, in order to search for possible counterparts. New EGRET data show that the COS–B emission probably corresponds to two localized γ-ray sources, 3EG J2016+3657 and 3EG J2021+3716. Spectral fits to these EGRET sources, assuming a power-law model, yield photon indices of ∼ 2 for each object. We examine archival ROSAT and ASCA X-ray data which overlap both EGRET error boxes, and find several point sources in the region to a flux limit of approximately 6.5 × 10 −13 erg cm −2 s −1. We conclude that the most probable candidate for 3EG J2016+3657 is the compact, variable, flat-spectrum radio and millimeter source B2013+370 (G74.87+1.22) which has blazar-like properties.