GW170817: a global astronomy event

A map of the approximately 70 light-based observatories that detected the gravitational-wave event called GW170817. On 17 August, the LIGO and Virgo detectors spotted gravitational waves from two colliding neutron stars. Light-based telescopes around the globe, including seven ESO telescopes, observed the aftermath of the collision in the hours, days, and weeks following. ESO's telescopes were pivotal in helping to pinpoint the location of the neutron stars and identify signs of heavy elements, such as gold, in the collision's ejected material.