Astronomers just spotted a brand-new supernova mere hours after it exploded, thanks to a robotic telescope and some smart computer algorithms. Now they’re scrambling to use as many telescopes as possible, on Earth and in space, to observe the star’s death throes.

New supernovae are not terribly rare, but this one is unique because it is so close — 21 million light years away — and it’s of a type that is crucial to astronomical measurements. The supernova, PTF 11kly, is the youngest ever detected.

It showed up in the spiral galaxy M101, the Pinwheel Galaxy, a rather large spiral (10 times the size of the Milky Way) located in the constellation Ursa Major, known to its friends as the Big Dipper. It’s a Type Ia supernova, a very bright type that is used for gauging distances among galaxies. The use of Type Ia supernovae as standard candles helped astronomers prove how rapidly the universe is expanding, and led to the discovery of dark energy. So it’s an important type, and the discovery of a super-new, superclose supernova is tantalizing news for astronomers.