Cos-B Observations of Localised Gamma-Ray Emission

The ESA gamma ray satellite COS-B has completed a survey of the galactic plane. The long exposure time combined with the effective angular resolution of about 2.5 deg. (FWHM) for gamma rays above 100 MeV permits a detailed study of the spatial distribution of the radiation. In four observation periods a search for localized gamma ray emission was performed. Each of the regions studied exhibits a significant fine structure superimposed on a diffuse emission along the galactic plane. This fine structure is consistent with the presence of a large number of high-energy gamma ray sources. A first catalog, including 11 so far unidentified gamma ray sources, is presented. The latitude distribution of these sources indicates a galactic nature.