The morphologies of wide-angle tailed ( WAT ) radio sources ( edge-darkened , C-shaped , FR I radio sources ) are the result of confinement and distortion of the radio lobes by the dense X-ray-emitting gas in clusters or groups of galaxies .
These radio sources are easily seen at high redshifts ( z \sim 1 ) in short-exposure images from the Faint Images of the Radio Sky at Twenty-cm ( FIRST ) survey .
Using a sample of approximately 400 WAT sources from the FIRST survey , we have discovered a number of high- z clusters .
Here , we present the highest- z cluster found so far using this method : 1137+3000 at z = 0.96 .
We include photometric and spectroscopic results .
Ten galaxies are confirmed at the cluster redshift , with a line-of-sight velocity dispersion of \sigma = 530 ^ { +190 } _ { -90 } km s ^ { -1 } , typical of an Abell richness class 0 cluster .