Compton Observatory OSSE studies of supernovae and novae

A primary objective of the Compton Observatory is the direct study of explosive nucleosynthesis in supernovae and classical nova. We have been fortunate in that three rare events have coincided, relatively speaking, with the Compton Observatory launch. Supernova 1987A, roughly a once per century event, was only 4 years old at launch and so the γ‐ray flux from 57Co decay was not much past its peak value. Supernova 1991T, a SN Ia which exploded within a few days of launch, is a once in a decade event. It offers as good a chance as we could reasonably expect to detect the 56Ni and 56Co decay which are supposed to be responsible for the impressive SN Ia display. Nova Cygni 1992, also a once in a decade event, might be our best change to detect γ‐rays from 22Na, a unique nucleosynthesis byproduct of the explosive hydrogen burning thought to power classical novae. The OSSE has detected 122 keV line and Compton scattered continuum photons from 57Co decay in SN 1987A. The total flux of 9×10−5 cm−2 s−1 corresponds...