A revised catalogue of EGRET γ-ray sources

Aims: We present a catalog of point γ-ray sources detected by the EGRET detector on the Compton Gamma Ray Observatory. We used the entire γ-ray dataset of reprocessed photons at energies above 100 MeV and new Galactic interstellar emission models based on CO, HI, dark gas, and interstellar radiation field data. Two different assumptions are used to describe the cosmic-ray distribution in the Galaxy to analyse the systematic uncertainties in source detection and characterization.
Methods: We applied a 2-dimensional maximum-likelihood detection method similar to that used to analyze the 3rd EGRET catalogue.
Results: The revised catalogue lists 188 sources, 14 of which are marked as confused, in contrast to the 271 entries of the 3rd EGRET (3EG) catalogue. We do not detect 107 sources discovered previously because additional structure is present in the interstellar background. The vast majority of them were unidentified and marked as possibly extended or confused in the 3EG catalogue. In particular, we do not confirm most of the 3EG sources associated with the local clouds of the Gould Belt. Alternatively, we found 30 new sources that have no 3EG counterpart. The new error circles for the confirmed 3EG sources largely overlap the previous ones, but several counterparts of particular interest discussed before, such as Sgr A*, radiogalaxies, and several microquasars are now found outside the error circles. We cross-correlated the source positions with a large number of radio pulsars, pulsar wind nebulae, supernova remnants, OB associations, blazars and flat radiosources and we found a surprising large number of sources (87) at all latitudes that have no counterpart among the potential γ-ray emitters.