The most powerful sources of gravitational waves are black hole mergers, which produce strong signals that can be detected by gravitational wave observatories.

Gravitational waves from black hole mergers typically have frequencies in the range of 10 Hz to 100 Hz.

Gravitational wave signals from black hole mergers typically last for a few seconds.

The expected rate of black hole mergers in the observable universe is a few per day.

The first gravitational wave signal detected by LIGO was GW150914, which was produced by the merger of two black holes.

The larger black hole in GW150914 had a mass of 36 solar masses.

The smaller black hole in GW150914 had a mass of 29 solar masses.

GW150914 was located 1.3 billion light-years away from Earth.

The second gravitational wave signal detected by LIGO was GW151226, which was also produced by the merger of two black holes.

The larger black hole in GW151226 had a mass of 14 solar masses.

The smaller black hole in GW151226 had a mass of 8 solar masses.

GW151226 was located 1.4 billion light-years away from Earth.

The third gravitational wave signal detected by LIGO was GW170104, which was produced by the merger of two black holes.

The larger black hole in GW170104 had a mass of 32 solar masses.

The smaller black hole in GW170104 had a mass of 20 solar masses.

GW170104 was located 880 million light-years away from Earth.