GW150914

GW150914: two black holes merging about 470 Mpc away, localized to 182 square degrees at 90%.

Arrived

2015-09-14

What merged

two black holes

Distance

470 ± 160 Mpc

50% credible region

51.3 square degrees

90% credible region

181.6 square degrees

The first. Two black holes of about thirty solar masses each, falling together 470 Mpc away, and the first time anybody had felt spacetime move. Nothing was ever seen of it in light and nothing was expected to be — black holes merging give off none. Only two detectors were running, so the sky it came from is this long arc rather than a patch: with a third instrument the same wave would have been pinned to a fraction of it.

Those two areas are credible regions rather than a boundary: the smaller holds half the probability and the larger nine tenths, and the tenth left over really is outside it. There is no right ascension and declination here because there is none to give — open it in the app to see the patch itself.

GWTC-1 sky localization for GW150914 — LIGO Scientific Collaboration and Virgo Collaboration

Open it in Bhagol — opens the app if you have it, and this page if you do not.