X-ray and gamma-ray observations of the galactic center.

X-ray and gamma-ray continuum observations and electron-positron annihilation line measurements of the Galactic center are reviewed. A unique hard X-ray and soft gamma-ray source located within a few degrees of Sgr A West are observed, displaying rapid variability. This variability suggests an origin in one or two sources. It is suggested that only the black hole model can account for the variability, the large flux, and the absence of other nuclear gamma-ray lines in this region. It is concluded that a black hole is probably present, although it is not necessarily located at Sgr A West.