Sep 11 2008
From The Space Library
A team of scientists led by Judith L. Racusin of Penn State University reported in the journal Nature their discovery that GRB 080319B had appeared extraordinarily bright because its jet had pointed almost directly at Earth. First sighted by NASA’s Swift satellite on 19 March 2008, GRB 080319B had been 7.5 billion light-years away from Earth, in the constellation Bootes. After Swift had sighted it, scientists around the globe had begun observing the GRB as it brightened to a magnitude of 5.3 on the astronomical brightness scale. For approximately 40 seconds, GRB 080319B had been visible to the naked human eye. Racusin’s team showed that the GRB’s jet had been composed of a narrow core, 0.4° wide, moving at almost the speed of light. A slightly slower jet, approximately 20 times wider than the core, had surrounded it. The team theorized that, if other GRB jets also have bright cores, astronomers might not often see them, because GRB jets rarely point in Earth’s direction, and their cores are very narrow.
NASA, “‘Naked-Eye’ Gamma-Ray Burst Was Aimed Squarely at Earth,” news release 08-223, 10 September 2008, http://www.nasa.gov/home/hqnews/2008/sep/HQ_08-223_Swift_Gamma_Ray_burst.html (accessed 26 July 2011); Andrea Thompson, “Scream of Black Hole’s Birth Detected Halfway Across the Universe,” Space.com, 10 September 2008, http://www.space.com/5826-scream-black-hole-birth-detected-halfway-universe.html (accessed 29 July 2011); see also J. L. Racusin et al., “Broadband Observations of the Naked-Eye .–Ray Burst GRB 080319B,” Nature 455, no. 7270 (11 September 2008): 183-188.
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