SPT-CL J0546-5345
is a very massive galaxy cluster, it is one of the most massive galaxy clusters ever found in the early universe. The cluster is thought to be located 7 billion light years away. It was discovered at the South Pole Telescope in 2008 by the Sunyaev-Zel'dovich-Effect. The cluster has a redshift of z = 1.067.  Follow-up studies using the Spitzer, Chandra, and optical telescopes allowed to identify cluster members and to measure the redshift. Using the velocity dispersion, the mass of the cluster has been estimated to 1015 solar masses.