*************************************************************************
   82131
   We propose to observe the X-ray luminous cluster of galaxies RXJ0152.7-
   1357 (z=0.833) in order to measure up to two temperature and iron
   abundance components. Our experiment has three main goals: (1) To
   determine whether this cluster, missed by the EMSS, is hotter than 8
   keV. If so, the EMSS is incomplete at this temperature and
   overestimates Omega_M. (2) To obtain two additional Lx-Tx measurements
   to compare to the local cluster Lx-Tx relation and constrain its
   evolution. (3) To measure the iron abundance of a z=0.8 cluster, to
   test whether an irregular system at z=0.8 has significant amounts of
   intracluster iron. This observation provides us with a first glimpse of
   a z=0.8 cluster environment which may NOT be a virialized system
   dominated by a single mass concentration.
 *************************************************************************