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    PR # 31549                                                                   
     We propose to examine 4 clusters within the Shapley supercluster. Acc       
     urate measurements of the temperature and surface brightness profiles       
      will provide strong constraints to the mass (which may help to expla       
     in the peculiar motion of the Local Group relative to the microwave b       
     ackground) and to the baryon fraction of the supercluster as a functi       
     on of radius. Such information will provide important insights into t       
     he formation and evolution of  structure over a range of scales.            
                                                                                 
                                                                                 
                                                                                 
                                                                                 
                                                                                 
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