GRB 090423 as seen by NASA's Swift satellite. The image is a composite of data from Swift's UV/Optical and X-Ray telescopes.
Credit: NASA/Swift/Stefan Immler
SYDNEY: A space-based telescope was blinded by the “brightest explosion ever witnessed by humanity”, Astronomers said.
“Just when we were beginning to think that we had seen everything that gamma-ray bursts could throw at us, this burst came along to challenge our assumptions about how powerful their X-ray emissions can be,” Neil Gehrels, from NASA’s Goddard Space Flight Centre, said in a statement.
Gamma-ray bursts are short-lived bursts of highly energetic radiation, which occur about once a day. The initial bright burst is followed by an ‘afterglow’ of longer wavelengths such as ultraviolet, optical and infrared.
Swift X-ray Telescope was ‘blinded’
The space observatory Swift has an X-ray telescope, set up in 2005 to observe and measure the brightness of gamma-ray bursts.
On June 21, a gamma-ray burst that had been travelling through space for approximately five billion years, was detected by the telescope. It ‘blinded’ the Swift X-ray Telescope and shut down the data-analysis software.
“So many photons were bombarding the detector each second that it just couldn’t count them quickly enough. It was like trying to use a rain gauge and a bucket to measure the flow rate of a tsunami,” said Phil Evans, a researcher at the University of Leicester in the United Kingdom, who helped write and monitor the data-analysis software used by the Swift Observatory.
Five times brighter
The researchers were able to measure the brightness of the gamma-ray burst, named GRB 100621A, by detecting the photons a distance away from the centre – the centre itself was too bright to measure. Using this technique, they found that GRB 100621A was 168 times brighter than a typical gamma-ray burst and five times brighter than the previous record holder.
Astronomer Brian Schmidt, from the Australian National University in Canberra believes the discovery of GRB 100621A “pushes the envelope by a long ways of how extreme the universe can be – it is intrinsically the brightest explosion ever seen by humanity.”
Schmidt advises that some of the most interesting work is yet to come – scientists need to determine the size of the star that caused this explosion – given the brightness of the explosion, it should be an impressive size, he said.
