COMPTEL upper limits for the 847 keV and 1238 keV g-rays of 56Co from SN1998bu

R. Georgii, S. Plüschke, R. Diehl, W. Collmar, G.G. Lichti, V. Schönfelder

H. Bloemen

J. Knödlseder

M. McConnell, J. Ryan

K. Bennett


The type Ia supernova 1998bu in M96 was observed by COMPTEL for a total of 88 days starting 26 days after the detection of the SN. A special mode improving the low-energy sensitivity, especially in the 847 keV line of 56Co was used. Spectral analysis is plagued by systematic uncertainties, especially around 1 MeV arising from the different background modeling techniques and event selection criteria to suppress a large part of the overwhelming background. We obtained images in the 847 keV and 1238 keV lines of 56Co, using an improved point spread function for the low-energy model. We do not detect SN1998bu. Low upper limits at both energies significantly constrain the standard supernova model for this event. Analysis, results and interpretation will be presented.

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On 16 Jul 1999, 09:19.