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LIGO and Virgo collaborations announce four new gravitational- waves detection


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Localizations of the various gravitational-wave detections in the sky. The triple detections are labelled as HLV, from the initials of the three interferometers (LIGO-Hanford, LIGO-Livingston and Virgo) that observed the signals.
Credits: UIB / LIGO / Virgo

The observatories are also publishing their first gravitational-wave events catalog

On Saturday 1st December 2018, scientists attending the Gravitational Wave Physics and Astronomy Workshop in College Park, Maryland, presented new results from searches for coalescing cosmic objects, such as pairs of black holes and pairs of neutron stars, by the LIGO and Virgo detectors. The LIGO and Virgo interferometers have now confidently detected gravitational waves from a total of 10 stellar-mass binary black hole mergers and one merger of neutron stars, which are the dense, spherical remains of stellar explosions. Seven of these events had been reported before, while four of the black hole detections are newly announced.

From September 12, 2015, to January 19, 2016, during the first LIGO observing run since undergoing upgrades in a program called Advanced LIGO, gravitational waves from three binary black hole mergers were detected. The second observing run, which lasted from November 30, 2016, to August 25, 2017, yielded a binary neutron star merger and seven additional binary black hole mergers, including the four new gravitational wave events being reported now. The new events are known as GW170729, GW170809, GW170818 and GW170823 based on the dates on which they were detected.

The Virgo interferometer joined the two LIGO detectors on August 1, 2017, while LIGO was in its second observing run. Although the LIGO-Virgo three-detector network was operational for only three-and-a-half weeks, five events were observed in this period. Two events detected jointly by LIGO and Virgo, GW170814 and GW170817, have already been reported.

One of the new events, GW170818, detected by the global network formed by the LIGO and Virgo observatories, was precisely pinpointed in the sky. The sky position of the binary black holes, located about 2.5 billion light-years from Earth, was identified with a precision of 39 square degrees. That makes it the next best localized gravitational-wave source after the GW170817 neutron star merger.

The collaboration

LIGO is funded by the NSF and operated by Caltech and MIT, who designed and built the project. The financial support for the Advanced LIGO project was led by the NSF with Germany (Society Max Planck Society), the United Kingdom (Science and Technology Facilities Council) and Australia (Australian Research Council-OzGrav) making important commitments and contributions to the project. More than 1,200 scientists from all over the world participate in the effort through the LIGO Scientific Collaboration, which includes the GEO Collaboration. An additional list of partners is available at

The Virgo Collaboration is made up of more than 300 physicists and engineers belonging to 28 different European research groups: six from the National Center for Scientific Research (CNRS) in France; 11 of the Istituto Nazionale di Fisica Nucleare (INFN) in Italy; two in Holland with Nikhef; the MTA Wigner RCP in Hungary; the POLGRAW group in Poland; Spain with IFAE and the Universities of Valencia and Barcelona (Institute of Sciences of the Cosmos, ICCUB); two in Belgium with the Universities of Liège and Leuven; Jena University in Germany; and the European Gravitational Observatory, EGO, the laboratory that houses the Virgo detector near Pisa in Italy, funded by the CNRS, INFN and Nikhef. A list of the Virgo Collaboration can be found at More information is available on the Virgo website at

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