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By Stephen Luntz

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Gamma Ray Burst at the Gates of Dawn
A 2009 gamma ray burst 500 million years after the Big Bang has been estimated as the oldest event ever observed.

Prof Brian Schmidt of the Australian National University’s Research School of Astronomy and Astrophysics says it is not easy to measure the age of such distant events, particularly those that don’t last long enough for detailed study. “What we definitely know is that this gamma-ray explosion was incredibly bright for a short period of time billions of light years ago, at the dawning of the birth of the universe, and that is certainly very exciting,” he says.

GRB 090429B was observed in the infrared by NASA’s Swift satellite. With no optical observations it was not possible to conduct the spectroscopy that would indicate its red shift precisely.

However, the absence of light at optical wavelengths is indicative of a very high red shift, with the cut-off caused by the absorption of light from gases located between Earth and the original explosion.

The location of the shortest wavelength of light Swift picked up from GRB 090429B suggests that its red shift is around 9.2, according to an Astrophysical Journal paper co-authored by Schmidt. The previous oldest event is estimated at a red shift of 8.4.

“With recent advances in technology, we are now getting to a stage where...

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