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   PR # 22188
    We propose to map the gravitational field of the rich Abell cluster  
    A401 by exploiting complementary X-ray data from ASCA and ROSAT      
    observations. In particular, the issue of subclustering and its      
    effect on determining the mass distribution will be addressed.  We   
    will constrain the shape of the gravitational potential and the      
    amount of mass in the cluster by using a method we have developed    
    predicated on the assumptions that the X-rays result from hot gas in 
    hydrostatic equilibrium with the cluster potential.  With the        
    superior spectral resolution of the ASCA data we will verify these   
    assumptions and precisely determine the temperature structure of the 
    gas; thus, significantly more accurate constraints on the cluster    
   mass distribution will be poss
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