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   PR # 41101
   Leo-I is the closest group of galaxies containing both a bright
   spiral (M96) and a bright elliptical (NGC 3379) and is as such
   well-studied - except in X-rays. The 200 kpc diameter HI ring
   orbiting NGC 3379/NGC 3384 put tight constraints on its interior mass
   and indicates that hot intragalactic gas could be the last unknown
   component in the mass balance. A deep pointing on NGC 3379/NGC 3384
   will detect this and give an important independent dynamical mass
   estimate. A pointing on M96 will clarify and possibly prove whether
   or not M96 is interacting with the HI ring and hence is a member of
   Leo-I. This is extremely important for the recent determination of
   the Hubble constant from HST observations of cepheids in M96.
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