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GCN Circular 16700

Subject
GRB 140817A: Fermi GBM Detection
Date
2014-08-17T18:48:16Z (10 years ago)
From
Oliver Roberts at UCD/Fermi <oliver.roberts@ucd.ie>
Oliver Roberts (UCD) and Charles Meegan (UAH) report on behalf of
the Fermi GBM Team:

"At 07:01:58.19 UT on the 17th of August 2014, the Fermi Gamma-Ray
 Burst Monitor triggered and located GRB 140817A (trigger 429951721
/ 140817293), which was also detected by the BAT and XRT on Swift
(Sbarufatti et al., Evans et al. and Cummings et al. 2014, GCNs
16695-99). The GBM on-ground location is consistent with the Swift
position. The angle from the Fermi LAT boresight is 124 degrees.

The GBM light curve consists of two bright peaks with a duration (T90)
of about 16 s (50-300 keV). The time-averaged spectrum from T0-9 s to
T0+16 s is adequately fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.64 +/- 0.19  and the
cutoff energy, parameterised as Epeak, is 130 +/- 11 keV.

The event fluence (10-1000 keV) in this time interval is
(5.03 +/- 0.04)E-06 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+5.8 s in the 10-1000 keV band is 10.6 +/- 0.5 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
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