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   PR # 22183
    The determination of the temperature of X-ray emitting gas in rich   
    clusters of galaxies at high redshifts provides important con        
    straints of models of the formation and evolution of large scale     
    structure. We propose ASCA observations of four galaxy clusters at   
    high redshift in order to determine their gas temperatures.  These   
    clusters are part of a sample of X-ray luminous high velocity        
    dispersion clusters for which we are also obtaining optical imaging  
    and spectroscopic and ROSAT high resolution imaging data. Our pro    
    posed observations, when combined with these other studies, will also
    allow comparison of cluster masses determined by several methods, in 
    order to determine galaxy, gas and dark matter mass distributions.   
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