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GCN Circular 15464

GRB 131108A: Fermi-LAT onboard detection of a burst
2013-11-08T21:39:17Z (11 years ago)
Judith Racusin at GSFC <>
J. L. Racusin (NASA/GSFC), S. Zhu (NASA/GSFC/UMD), D. Kocevski (NASA/GSFC/ORAU), M. Ohno (Hiroshima), 
N. Omodei (Stanford), E. Troja (NASA/GSFC/CRESST) and G. Vianello (Stanford), report on behalf of the Fermi LAT 

At 20:41:55.76 UTC on November 8, 2013, Fermi LAT triggered onboard on high energy emission from GRB 131108A.  
The burst was also detected by GBM (trigger 131108863/405636118), and triggered an autonomous repoint of the 
spacecraft.  This is the first onboard trigger since 2009, indicating a potentially rare and exciting event.

The onboard location is R.A., Dec. 156.47, +9.90 (J2000) with an approximate error radius of 0.5 deg, seeded by the 
GBM detected position.  This was 27 deg from the LAT boresight at the time of the trigger. We anticipate providing a 
refined location within the next 12-15 hours when the LAT science data for this burst is downlinked and processed.

The Fermi LAT point of contact for this burst is Masanori Ohno (

A Swift TOO request has been approved.

The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 
GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific 
institutions across France, Italy, Japan and Sweden.
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