On April 26 2019, scientists at the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo Interferometer detected gravitational waves from a possible black hole-neutron star collision thought to have taken place 1.2 billion light years away. The event was observed by both LIGO observatories, based in Louisiana and Washington state in the USA, and the Virgo facility based in the European Gravitational Observatory (EGO) in Italy.