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   52092
   HB 21 is a compostie supernova remnant with centrally filled X-ray and
   shell-like radio morphology. While a hypothesis invoking evaporation of
   interior clouds appears most consistent with X-ray data, the shock
   fronts of virtually all composite SNR seem to be interacting with large
   clouds as well. HB21 is no exception, with the interaction producing
   clumpy filaments in the infrared and high velocity HI gas. We propose
   two ASCA pointings at the interior of HB21. The data will be used to
   investigate if the interaction with the cloud is directly responsible
   for the central X-ray emission, as well as to measure the temperature
   and density profiles.
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