Astronomers Spy Brightest Galactic Blast

Sept. 10, 2008 -- Last March our planet looked straight down the barrel when one of the universe's most deadly kinds of stellar artillery fired -- and we lived to tell about it.

The March 19 cosmic cannon was a jet of powerful gamma rays which shot out matter at speeds just a hair shy of the universal speed limit -- that of light.

The explosion, which occurred not far from the handle of the Big Dipper, was even more remarkable because it was accompanied by enough visible light to be seen briefly with unaided human eyes. That's despite the fact that the dying mega-star that created the blast was in another galaxy, a whopping 7.5 billion light-years away.

"It definitely broke some records," said astronomer Dieter Hartmann of Clemson University in South Carolina. "The luminosity was a million times that of the whole galaxy, which is astounding."

It was so bright, in fact, that at first one of its discoverers thought something was wrong, said Judith Racusin, a graduate student at Pennsylvania State University. Racusin is the lead author of a paper on the discovery in the Sept. 11 issue of the journal Nature.

The gamma ray burst, dubbed GRB 080319B, was detected by NASA's Swift satellite, which is equipped specifically to spot such events quickly. Both Swift's X-Ray Telescope and its UltraViolet/Optical Telescope were blinded by the unusually bright blast.

Ensuing observations around the world with other satellites and ground-based telescopes collected an unprecedented amount of data from across the electromagnetic spectrum. No fewer than 92 researchers have combined their work to publish the Nature paper.