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   PR # 21168
     There is a strong indication of rapid cluster evolution.  However, X
    -ray data, other than total X-ray luminosity, have so far been too   
    sparce to investigate the evolutionary effect any systematically.    
    Withuse of the unique capabili- ties of ASCA, this proposal aims at a
    study of the evolutionary effect with  respect to temperature, metall
    ic abundances and total mass for three clusters in the distance range
    z=0.22 - 0.26.These clusters were carefully selected  from the so-far
    most complete list of clusters obtained from ROSAT All Sky Survey,   
    hence they are very secure for obtaining good quality data.  Combined
    with the ROSAT results of these clusters, the proposed observation   
    will  provide a best set of cluster data to study the evolutionary   
   effect.                       
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