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   PR # 11070
    The Cygnus Loop is one of the most studied SNRs. The shape is a typic
    al shell structure with a diameter of 3 d. In X-ray regions,it is one
    of the most strongest sources below 1 keV. At PVphase,we observed the
    centre and the NE limb and got exciting results. The spectrum shows
    many emission lines (OVII,OVIII,Fe-L,NeIX,Mg,Si,S and more). However
    we observed only restricted areas in comparison with its size. The NE
    limb has a uniform shell,but some other shells are full of varieties.
    Their varieties come from the various interactions between the shock
    wave and the interstellar matter or molecular clouds. At AO-1, we pro
    pose to observe above areas (SW,S, W limb).We can study the evolution
    of the shock wave since its structure is very clear and the size is
   big enough to study in detail.
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