GRANAT images of the Galactic Center region in 4–1300 keV band: Localization of the possible candidate for 511 keV source

The most important results of the Galactic Center observations by GRANAT during 1990 are: discovery of new very hard X‐ray source GRS1758–258 in 40 arcmin from GX5‐1, strong variability of Sgr A* in 4–30 keV energy range, unambiguous detection of 1E1740.7–2942 as the brightest hard X‐ray source in the vicinity of the Galactic Center and discovery of the variable hard component in its spectrum. The shape of the latter allows one to suppose the relation of this component with electron‐positron annihilation. The hardness of the spectra of both 1E1740.7–2942 and GRS1758–258 gives strong arguments to include them to the list of black hole candidates.