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   PR # 21159
    We proporse the observation of three distant clusters of galaxies at 
    z=0.2-0.3. The prime purpose of this observation is to investigate a 
    relarionship between temperature of ICM and X-ray luminosity for high
    z clusters and compare it with the one for low z clusters. If there  
    is difference between them, it becomes much steadier evidence for the
    evolution  of cluster of galaxies than the evolution of luminosity   
    function found by  Gioia etal. The second purpose is to investigate  
    the relationship among gas  mass, summention of mass of member galaxi
    es and gravitational mass for high z  clusters and compare it with   
    the one for low z clusters. A more specific  interest is to obatin   
    mass function for high z cluster and determine  cosmological         
   parameters with it.           
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