The nature of an exceptional high-redshift strong lens

We have recently identified an exceptional strong lensing cluster at z1.335: Abright giant arc with a spectroscopically measured redshift z3.29 is seen at alarge angular radius of 18 and two additional multiply lensed backgroundsources have been identified in recent HST imaging. XMM data are needed todetermine whether this remarkable lensing strength is generated by a singlemassive cluster with a deep potential well or projection effects of multiplecorrelated or uncorrelated structures along the line of sight. We request jointChandra observations to identify exclude point sources and VLT MUSE observationsto search for lineofsight structures in the redshift distribution of galaxies. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]