CGRO OSSE OBSERVATIONS OF THE CASSIOPEIA-A SNR/

We present all OSSE observations to date of the Cas A supernova remnan t. The objectives are to detect the Ti-44 lines, one of which has been reportedly detected by COMPTEL, and the hard X-ray continuum above 40 keV, as indicated by HEAO-A2 measurements. Our best fit flux in each of three Ti-44 lines is (+1.76 +/-(1.51)(1.48)) 10(-5) gamma cm(-2) s( -1) with chi(nu)(2) = 1.01, d.o.f.=1780. The implied Ti-44 mass of sim ilar to 10(-4) M. is compatible with explosive nucleosynthesis calcula tions. OSSE detected also a continuum below 200 keV at better than 4 s igma confidence level with a flux of similar to 9 10(-4) gamma cm(-2) s(-1) MeV(-1) at 100 keV. This continuum can be fitted equally well wi th a power law, an exponential, or a thermal bremsstrahlung model. The implied temperature of kT approximate to 35 keV can be interpreted as the emission from the shocked circumstellar matter (CSM) by the prima ry blastwave of the supernova. Alternatively, the continuum can also b e interpreted as bremsstrahlung from accelerated electrons that are al so producing the observed radio emission.