http://news.theage.com.au/cosmic-blast-75-billion-years-old-seen-with-naked-eye/20080321-20uq.html

NASA measured the explosion as having occured 7.5 billion years ago, before Earth was formed and more than halfway across the visible universe.

Until now the most luminous object visible with the naked eye was galaxy M33, a "relatively short" 2.9 million lightyears from Earth.

The explosion seen Wednesday "blows away every gamma ray burst we've seen so far," said Neil Gehrels of Goddard Space Flight Center.

Gamma ray bursts occur when huge stars use up all their fuel and their core collapses, forming black holes or neutron stars that release bursts of gamma rays, ejecting particles into space at nearly the speed of light and generating afterglows.

The burst, named GRB 080319B, was among a record four bursts detected by Swift on Wednesday, the same day of the death of prolific science fiction writer Arthur C. Clarke who wrote "2001: A Space Odyssey."

"Coincidentally, the passing of Arthur C. Clarke seems to have set the universe ablaze with gamma ray bursts," said Swift team member Judith Racusin of Penn State University.