Astrophysicist Ian Ha from temple University (USA) have calculated the mass of stars, which then turned into black holes whose collision gave rise to a gravity wave event GW150914. According to estimates Ha, before turning into black holes, the pair of stars was in 70 and 55 times heavier than the Sun, and at the time of his birth the lights were 93 and 73%, respectively, heavier than the nearest star to Earth.
Event GW150914 was registered on 14 Sep 2015 at 13:51 Moscow time on the two detectors of the twin laser interferometric gravitational wave Observatory LIGO, located in Livingston (Louisiana) and Hanford (Washington) in the USA.
The observed perturbation generated by a pair of black holes (29 and 36 times heavier than the Sun) in the last fraction of a second before they merge into more massive rotating gravitational object (62 times heavier than the Sun). Merging black holes occurred 1.3 billion years ago (so much time gravitational pull was extended to the Land).