Gris Observations of Supernova 1987A: Resolution of the 1238 Kev Gamma-Ray Line.

Supernova 1987A has produced observable gamma-ray line and continuum emission since 1987 Aug. sup (1,2,3,4,5,6,7,8,9). This radiation originates primarily from the decay of radioactive sup (56) Co, a daughter of sup (56) Ni that was created by explosive nucleosynthesis within a few seconds after the initial gravitational collapse. In this paper we report the first results from the maiden flight of the Gamma-Ray Imaging Spectrometer (GRIS), a new second-generation high-resolution gamma-ray spectrometer that provides a significant improvement in gamma- ray line detection and resolution capabilities over currently available instrumentation SN1987A was observed for a period of 11.1 hr on 1 May 1988. Line emission at 1238 keV and continuum emission (to be reported elsewhere) from 60 to 800 keV were detected sup (10).