After the signal being simultaneously detected by the two LIGO detectors in USA and VIRGO in Italy, the position of the event could be precisely triangulated and scientists could locate it in a relatively small patch in the southern sky. Fermi Observatory was able to provide a localization that was later confirmed and greatly refined with the coordinates provided by the LIGO-Virgo detection. With these coordinates some 70 ground- and space-based observatories could point their telescopes to the event and perform follow-up observations in all the range of the electromagnetic spectrum.
The observed event was the merging of two neutron stars located at the relatively close distance of about 130 million light-years from Earth. As these neutron stars spiraled together, they emitted gravitational waves that were detectable for about 100 seconds. This is a much longer period than when two black holes collide, providing scientists with more detailed information on gravitational waves. After the collision, a flash of light in the form of gamma rays was emitted and seen on Earth about 2 seconds after the gravitational waves. In the days following the smashup, other forms of or electromagnetic radiation were also detected.
This observation will also represent a remarkable increase in our knowledge on neutron stars, in particular concerning the production of heavy metals such as gold and platinum, as well as on other astrophysical phenomena such as the origin of gamma ray outbursts.
More information: NSF press release
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