James R. Graham tex2html_wrap_inline128 & Bernd Aschenbach tex2html_wrap_inline130
tex2html_wrap_inline128 Astronomy Department, University of California, Berkeley, CA 94720.
tex2html_wrap_inline130 Max-Planck-Institute für Extraterrestriche Physik, Garching bie München, Germany.


We have almost completed a joint US/German campaign to map the entire Cygnus Loop supernova remnant at the maximum practical spatial resolution permitted by the ROSAT-HRI. Substantial progress was made in AO5 and AO6, and we hope to complete the remaining 30% of this unbiased survey during AO7. The Cygnus Loop is the prototype for an ISM-interaction dominated SNR, and as such, provides basic physical information on one of the fundamental mechanisms which shapes the interstellar medium.

We chose the Cygnus Loop because it offers a unique opportunity to learn the details of the interaction of a blastwave with interstellar clouds. We have been rewarded by an unprecedented view of the gas dynamic processes that occur when a blastwave strikes a cloud. The global view afforded by the ROSAT-HRI mosaic highlights the inhomogeneity of the ISM and the pivotal nature of blastwave-cloud interactions in determining the X-ray morphology of the Cygnus Loop. A combination of the ROSAT-HRI survey and a deep H tex2html_wrap_inline136 mosaic provide definitive evidence that the Cygnus Loop was formed by an explosion within a preexisting cavity. A by-product of this study is an inventory of the interstellar medium in the vicinity of the Cygnus Loop.

Finally, this survey provides a unique asset for planning observations which make full use of the very high spatial resolution of AXAF.

james r. graham 649

Mon May 27 17:32:24 PDT 1996