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   PR # 21049
    We propose to observe 3C400.2. This SNR has a shell in radio while it
    is a center filled in X-ray.  Since there is no point souce in radio,
    we can expect a thin thermal emission in X-ray.  If the evolution of 
    the SNR follows to the Sedov solution, we can expect the shell struct
    ure in X-ray.  This is also true even if there is a plausible density
    gradient in the ambient gas structure before the SN explosion. If the
    emission from the cloud evaporation dominates that from the blast    
    wave, the center filled structure can be possible.  The purpose is to
    study the temperature and abundance gradient through the SNR. It will
    give us the clue which model is better.  The SNR showing a center    
    filled in X-ray and a shell in radio may be attributed to the cloud  
   evaporation inside the remnant
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