OSSE Observations of 1E 1740.7=2942 in 1992 September
NAVAL RESEARCH LAB WASHINGTON DC
Pagination or Media Count:
We present data on the galactic X-ray source 1E 1740.7-2942 from the Oriented Scintillation Spectrometer Experiment OSSE on board NASAs Compton Gamma Ray Observatory. Episodes of increased low- energy gamma radiation have been reported from this source, including 1-day events in 1990 October and 1992 September. These events, of intensity 7 x 10exp -3 and 4 x 10exp -3 photons cmexp-2 sexp -1, respectively, have been interpreted as broadened and redishifted position annihilation radiation. OSSE conducted observations of the Gallactic Center region during a 21 day interval from 1992 September 17 thru 1992 October 8. This includes the time of increased 200-450 keV emission from IE 1740.7-2942 reported by SIGMA. The OSSE observations do not confirm this event. For the specific outburst recorded by SIGMA, 1992 Sep. 19.42-20-58 UT, OSSE data provide an upper limit 3sigma of 2.4 x 10exp-3 photons cmexp-2 sexp-1.