GRB 050904
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GRB 050904 is the most distant gamma ray burst observed as of 2005. The GRB has a redshift of z=6.295, making it the second most distant object ever observed (the most distant being the quasar SDSS J1148+5251, at redshift 6.43). It is located in Pisces. It was detected on September 4, 2005 by the Swift Gamma-Ray Burst Mission
Astronomers Dr. Daniel Reichart and Joshua Haislip from UNC-Chapel Hill observed the event with the SOAR Telescope located on Cerro Pachon, Chile. Using the Ohio State InfraRed Imager/Spectrometer (OSIRIS) they found evidence suggesting that the burst was the most distant ever observed. They were the first to notify the astronomical community of its high-redshift nature.
The GRB is 13 billion light years away (in the sense that the light it emitted has taken 13 billion years to traverse the universe to reach us). When this GRB exploded, the age of the universe (according to the most recent estimates) was only 900 million years.
The duration of the burst was 200 seconds, longer than the typical 10 seconds. However, through the effect of time dilation due to the expansion of the universe, the intrinsic duration of the burst was stretched so that the burst appeared longer in the observer's frame of reference.
In papers published in March 2006, the burst was deduced to be caused by a massive star collapsing into a black hole.