27 Sep 2017 — The Virgo Collaboration and the LIGO Scientific Collaboration have jointly observed the merger of two black holes. This is the fourth confirmed detection of a binary black hole merger, and the first detection made using a network of three interferometers.
The detected waves—observed on August 14th, 2017 at 10:30:43 UTC (6:30AM EDT) —were produced by a pair of black holes with 31 and 25 solar masses. They merged to produce a spinning black hole of 53 solar masses. Combining the signal from Virgo with the signal observed in the two LIGO observatories improved the sky localization of the source by over a factor of 10.
For more information see the press release, the ligo.org detection page for GW170814, and the LIGO Lab page for GW170814.