Black holes are elusive objects - no firmly established properties, some scientists even claim they don't exist. Gravitational waves are equally elusive, so the following detailed tale about black holes was told by LIGO conspirators, not by gravitational waves:

http://www.nytimes.com/2016/02/12/sc...-einstein.html
"The frequency of the chirp was too low for neutron stars, the physicists knew. Detailed analysis of its form told a tale of Brobdingnagian activities in a far corner of the universe: the last waltz of a pair of black holes shockingly larger than astrophysicists had been expecting. One of them was 36 times as massive as the sun, the other 29. As they approached the end, at half the speed of light, they were circling each other 250 times a second.. And then the ringing stopped as the two holes coalesced into a single black hole, a trapdoor in space with the equivalent mass of 62 suns. All in a fifth of a second, Earth time."

Pentcho Valev