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   PR # 21539
    We propose to examine 4 clusters within the Shapley Supercluster     
    (which may contribute to the peculiar motion of the Local Group      
    relative to the microwave background). Accurate measurements of the  
    temperature and surface brightness profiles will provide strong      
    constraints on the masses of clusters, on the baryon fraction of the 
    supercluster as a function of radius and help constrain the total    
    mass of the supercluster. This information will provide important    
    insights into the formation and evolution of structures over a range 
    of scales.                                                           
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