... Tonight's Sky . ... Behemoth black hole found in an unlikely place . ... black holes . ... Clocking the rotation rate of a supermassive black hole . A recent observational campaign allowed a team of astronomers to measure accurately the rotational rate of one of the most massive black holes in the universe. ... This effect arises from Einstein's General Theory of Relativity, and its precessional rate depends mainly on the two black hole masses and the rotation rate of the more massive black hole. ...