2008ApJ...688..852H

The broad-line radio galaxy 3C 111 has been suggested as the counterpart of the γ-ray source 3EG J0416+3650. While 3C 111 meets most of the criteria for a high-probability identification, like a bright flat-spectrum radio core and a blazar-like broadband SED, in the Third EGRET Catalog, the large positional offset of about 1.5° put 3C 111 outside the 99% probability region for 3EG J0416+3650, making this association questionable. We present a reanalysis of all available data for 3C 111 from the EGRET archives, resulting in probable detection of high-energy γ-ray emission above 1000 MeV from a position close to the nominal position of 3C 111, in two separate viewing periods (VPs), at a 3 σ level in each. A new source, GRO J0426+3747, appears to be present nearby, seen only in the >1000 MeV data. For >100 MeV, the data are in agreement with only one source (at the original catalog position) accounting for most of the EGRET-detected emission of 3EG J0416+3650. A follow-up Swift UVOT/XRT observation reveals one moderately bright X-ray source in the error box of 3EG J0416+3650, but because of the large EGRET position uncertainty, it is not certain that the X-ray and γ-ray sources are associated. A Swift observation of GRO J0426+3747 detected no X-ray source nearby.