On 2017 August 17, for the first time both gravitational and electromagnetic waves from a single source have been observed. In fact, the detection of a gamma-ray transient 1.7 s after the gravitational wave signal and of a bright optical transient less than 11 hours later led to the localization of the source in the galaxy NGC 4993 located at about 40 Mpc. Following early non-detections, X-ray and radio emission were also discovered at the same celestial location about 9 and 16 days, respectively, after the merger. The Sardinia Radio Telescope was involved in the large campaign of observations which were performed across the entire electromagnetic spectrum during the 45 days following the event. The unprecedented data sets collected by more than 80 instruments in the world further supported the interpretation of the gravitational wave event as due to a binary neutron star coalescence.

Published in The Astrophysical Journal Letters, Volume 848, Issue 2, article id. L12, 59 pp. (2017).