  We report the serendipitous discovery of a giant grvitational arc in the
Abell Supplementary cluster S295 during optical follow-up observations of
clusters detected in the ROSAT All-Sky Survey. The cluster has a redshift
z=0.3007 and a velocity dispersion of about 900 km/sec. This is the first giant
arc newly found in a ROSAT Survey cluster, indicating the potential advantage
of searching for giant arcs in X-ray selected clusters.
