Search for gamma-ray line emission from supernova SN 1991T with COMPTEL

The imaging Compton telescope COMPTEL on the Compton observatory CGRO measures γ‐rays in the energy range 0.7–30 MeV with an energy resolution of 9.7% FWHM at 1 MeV. From June 15 to 28 and again from October 3 to 17, 1991 the region containing the supernova SN 1991T was observed. A search for γ‐ray line emission from the supernova was performed. No line emission was detected. Upper limits for the two predicted lines at 847 keV and at 1.238 MeV could be derived. These limits were compared with the predictions of several theoretical models. Two of the models predict flux levels just above our upper limits.