Number 18 (Story #3), January 23, 1991 by Phillip F. Schewe and Ben Stein GAMMA-RAY ANNIHILATION RADIATION from the center of the Milky Way, seen off and on since 1977 by balloon-borne detectors (Marvin Levanthal, Bell Labs, 201-582-3448), has now been observed by the Soviet-French gamma-ray satellite GRANAT. Actually sitting some 100 light years from dead center, the source of gammas, which arise from the annihilation of electrons and positrons and which therefore have a characteristic energy of 511 kev, may harbor a relatively small (hundreds of solar masses) black hole. This is in addition to the black hole (perhaps a million solar masses) which may lurk at the very center of the galaxy. Evidence for this will be sought by GRANAT and by the U.S. Gamma-Ray Observatory, due to be launched later this year. (Science, 11 Jan. 1991.)