High-resolution maps of two supernova remnants.

The general morphologies of two supernova remnants (SNRs), G355.9-2.5 and G351.3+0.2, studied with the Monlonglo Observatory Synthesis Telescope (MOST), are discussed. The two SNRs were observed in August 1982, shortly after the 22-arcmin field size for full synthesis became available. In both sources, the new maps reveal an overall ring appearance attributable to a shell structure. Measured and derived parameters for the SNRs are tabulated. The map of G355.9-2.5 reveals a prominent ring structure which was only hinted at by earlier observations; the eastern quadrant of the shell appears to have suffered what can be described as a 'blow-out'. Observations of this SNR support the interpretation that most SNRs are expanding into cooler denser regions and therefore undergo significant decelerations in a few hundred years. Distortions of the shell of G351.3+0.2 from circularity are even more acute and suggest that the interstellar medium nearer the galactic plane may be more inhomogeneous. High-resolution CO and H I observations of the surroundings should be interesting.