090424

We have recently identified an exceptional strong lensing cluster at z=1.335: A bright giant arc with a spectroscopically measured redshift z=3.29 is seen at a large angular radius of 18 and two additional multiply lensed background sources have been identified in recent HST imaging. XMM data are needed to determine whether this remarkable lensing strength is generated by a single massive cluster with a deep potential well or projection effects of multiple correlated or uncorrelated structures along the line of sight. We request joint Chandra observations to identify exclude point sources and VLT MUSE observations to search for line-of-sight structures in the redshift distribution of galaxies. [truncated! Please see actual data for full text]