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   72082
   We propose to observe the shells of two old SNR's: CTB 80 containing
   the 40 millisecond pulsar, PSR 1951+32; and W50 containing the jet
   source, SS433. While the X-ray spectrum from these shells is poorly
   measured with ROSAT, the broadband coverage of ASCA combined with its
   high spectral resolution will allow us to test for the thermal nature
   of the spectrum by detection of emission lines.The spatially resolved
   spectroscopy will also enable us to localize possible regions of non-
   thermal X-ray emission, whose evidence exists from the combined radio
   andX-ray morphology. Determining whether the spectrum is entirely
   thermal ornot will allow us to 1) probe the energies dumped in the
   remnants and 2) test for cosmic ray acceleration in old rejuvinated
   shells.
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