Summary

The Second EGRET catalog contains 129 sources. Their locations, in galactic coordinates, are shown in Fig. 5, where the size of the symbol represents the highest intensity seen for the source. The 38 sources with consist of 5 pulsars, one solar flare (bright enough to be detected in the maps as a source), and 32 unidentified sources. The 91 sources with include the LMC, 40 sources identified with active galactic nuclei (AGN) with high confidence, 11 sources which may be AGN, and 39 unidentified sources.

31 sources reported in the first EGRET catalog do not appear in this catalog. 5 of these are sources which were identified with AGN; all 5 of these now have statistical significance just below the threshold for the present catalog.

The presence of a high fraction of unidentified sources in the catalog indicates the need for continuing studies, not only with EGRET but across the electromagnetic spectrum, in order to find counterparts capable of producing this high-energy radiation.