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   51218
   Clusters of galaxies as the largest, well defined building blocks of
   the Universe are important cosmological probes. In particular the
   cluster X-ray temperature function can be used to constrain the power
   spectrum of the primordial density fluctuations in the Universe. The
   hottest clusters are important in these models. In a recent redshift
   survey of clusters detected in the ROSAT All Sky Survey we found A2667
   to be an extremely X-ray luminous, distant (z=0.234) cluster with an
   expected temperature around 10 keV. There are only three other clusters
   which are similarly bright and distant (all of which were already
   observed with ASCA). Therefore we propose to observe A2667 with ASCA.
   The cluster is also a good candidate for a search for gravitationally
   lensed images and for the SZ-effect.
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