Using ESO’s Very Large Telescope and the W.M. Keck Observatory, astronomers at the Ecole Polytechnique Fédérale de Lausanne in Switzerland and the California Institute of Technology, USA, have discovered what appears to be the first known triplet of quasars. This close trio of supermassive black holes lies about 10,5 billion light-years away towards the Virgo constellation.

https://www.eso.org/public/news/eso0702/

http://www.keckobservatory.org/recent/entry/first_triple_quasar_discovered_at_w._m._keck_observatory/