OSSE OBSERVATIONS OF ACTIVE GALAXIES AND QUASARS

We present a summary of OSSE observations of galaxies and quasars that have been carried out during the Phase 1 all-sky survey by the Compton Observatory. The OSSE instrument has detected continuum emission from several Seyfert galaxies and quasars. Seyfert 1 galaxies make up the majority of the detections, typically at energies below 300 keV, with the measured spectra generally compatible with power-law continuum models with photon spectral indices around --2, or with thermal emission models with temperatures around 50 keV. The quasars generally have harder spectral indices than the Seyfert galaxies. With the exception of Centaurus A and NGC 4151, there is little evidence of significant flux variability in the OSSE data sets for most of the Seyfert galaxies observed. In some cases, the OSSE detections are at flux levels significantly below those reported for previous observations. While the analysis of the complete set of Phase 1 OSSE observations of active galaxies is still in progre..