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Session 48 - Gamma Rays & X-ray Instrumentation.
Display session, Thursday, January 08
Exhibit Hall,

[48.02] High-Energy Gamma Rays from Centaurus A: A Status Report

P. Sreekumar, J. A. Esposito (USRA/NASA/GSFC), D. L. Bertsch, R. C. Hartman, S. D. Hunter, D. J. Thompson (NASA/GSFC), D. A. Kniffen (Hampden-Sydney), G. Kanbach, H. A. Mayer-Hasselwander, O. Reimer (MPI für Extraterrestrische Physik), Y. C. Lin, P. F. Michelson, P. L. Nolan (Stanford University), S. Bloom, A. W. Chen (NRC/NASA/GSFC), R. Mukherjee (Barnard College and Columbia U.)

The nearest radio galaxy, Centaurus A has been observed numerous times by the EGRET instrument on board the Compton Gamma Ray Observatory. Early observations showed the presence of a point source in the vicinity of Cen A; however, poor statistics and uncertainties in the strong galactic diffuse background emission near the source prevented a clear identification of the gamma-ray source with Cen A. Using the cumulative exposure from the last 5 years of EGRET observations, the identification appears more likely. There is no evidence for time variablity in the emission above 100 MeV unlike that at lower energies. Furthermore, all previous EGRET detections of active galaxies belong to the blazar-class, most of which show variability at gamma-ray energies. The multiwavelength spectrum including OSSE and COMPTEL measurements is examined and its implications on proposed models to explain the high-energy emission are discussed.

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