Boom. A star is dead.

On Sept. 20, 2016, Victor Buso, an amateur astronomer in Rosario, Argentina, was checking out the new camera on his telescope by taking pictures of a nearby spiral galaxy when a star within it went off in a supernova explosion.

Within hours, and prompted by Buso’s good fortune, professional astronomers around the world trained their big telescopes on the galaxy, known as NGC 613, about 80 million light-years from here in the constellation Sculptor. It was a rare instance in which astronomers were able to see the beginning of a supernova, when one of the most massive stars in the universe ends its life in one of the most violent events nature can cook up.

Most supernovas are far away and don’t call attention to themselves until their funeral pyre explosions are well underway. In this case, astronomers were able to record what they call the “breakout,” when a shock wave radiating from a star’s core, which has probably collapsed into a black hole, reaches the surface of the poor star and brightens it catastrophically.

“It’s like winning the cosmic lottery,” said Alex Filippenko, in a news release from the Keck Observatory in Hawaii, where Filippenko, of the University of California, Berkeley, has been tracking the supernova.

The astronomers, who reported their findings today in Nature, said the original star had probably been about 20 times as massive as the sun, but had blown most of that mass off into space before the decisive explosion began.