Joint Virgo-Ligo observation of a black hole merger


On September 27, 2017, the Virgo Collaboration and the LIGO Scientific Collaboration announced the first gravitational-wave signal observed by a network of three laser interferometers.

On September 27, 2017, the European gravitational waves observatory VIRGO together with the US observatory LIGO announced a joint observation of a black hole merger. The signal was seen in coincidence in the VIRGO and in both LIGO interferometers on August 17. It is interpreted as the merger of two black holes of, roughly, 25 and 30 solar masses, happening at a distance of about 550 Mega parsec from us.

This is the fourth observation of a black hole merger, which thus are slowly becoming routine. But it is a new milestone in the history of gravitational wave astronomy, in that this is the first simultaneous observation in three instruments; recall that VIRGO has not been online during the previous LIGO detections. That all 3 detectors were able to register the signal does not only make it possible to locate the region of the source more precisely, but also shows that gravitational wave astronomy is on the way to become a new tool to explore the universe.

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