Gamma-ray monitoring of AGN and galactic black hole candidates by the Gamma-Ray Observatory

The Burst and Transient Spectroscopy Experiment (BATSE) on the Compton Gamma‐Ray Observatory has a powerful capability to provide nearly uninterrupted monitoring in the 25 keV–10 MeV range of both AGN and Galactic black hole candidates such as Cygnus X‐1, using the occultation of cosmic sources by the Earth. Progress in background modeling indicates that the data accept region, or fit window τ, around the occultation step can be substantially increased over that conservatively assumed in earlier estimates of BATSE’s Earth occultation sensitivity. We show samples of large‐τ fits to background and source edges. As a result we expect to be able to perform long‐term monitoring of Cygnus X‐1 and many of the brighter AGN for the duration of the CGRO mission.