EGRET Source Positions on the Sky
This diagram indicates the positions on the sky of EGRET detected sources of celestial gamma-rays at energies above 100 MeV. The source positions are plotted in Galactic coordinates with color-coded classifications. As indicated, the EGRET instrument has now identified more than sixty members of a new class of active galaxies known as blazars. These objects are characterized by extremely variable gamma-ray emission, and emit most of their energy in the gamma-ray regime. Only one extragalactic object, the quasar 3C273, was seen in gamma-rays prior to the Compton Observatory launch, in 1991. Also shown are the positions of several pulsars, and many unidentified sources detected by EGRET. The Large Magellanic Cloud (LMC) is also seen at gamma-ray energies.
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