  We present X-ray and optical observations of the z=0.52 galaxy cluster
RBS380. This is the most distant cluster in the ROSAT Bright Source catalog.
The cluster was observed with the CHANDRA satellite in September 2000. The
optical observations were carried out with the NTT-SUSI2 camara in filters V
and R in August and September 2001. The preliminary conclusions are that we see
a very rich optical galaxy cluster but with a relative low X-ray luminosity. We
also compare our results to other clusters with similar properties.
