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   52190
   We propose offset reobservations of A3571 and A2256 to measure their
   gas temperatures out to r=1.6 and 2 Mpc, respectively. ASCA temperature
   maps suggest that these clusters have been undisturbed in the past.
   This makes them good candidates for a reliable determination of mass
   profiles at large radii, which addresses a number of interesting
   cosmological issues. There are very few clusters for which such
   measurements are feasible with ASCA. A3571 has a moderate cooling flow
   which makes it a rather typical cluster. At the proposed radius in
   A3571, we expect to see a temperature decline like the one we detected
   in several other clusters -- if this phenomenon is indeed common. The
   proposed and existing A2256 data will provide a cluster temperature
   profile of unprecedented quality.
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