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GCN Circular 21491

GRB 170813A: Fermi GBM observation
2017-08-15T21:25:46Z (7 years ago)
Suraj Poolakkil at UAH <>
S. Poolakkil (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 01:13:25 UT on 13 August 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170813A (trigger 524279593/ 170813051),
which was also detected by the Swift/BAT (Page et al. 2017, GCN 21468).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 41

The GBM light curve shows multiple pulses
with a duration (T90) of about 112 s (50-300 keV).
The time-averaged spectrum from T0-2.0 s to T0+23.6 s is
adequately fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.52 +/- 0.11 and
the cutoff energy, parameterized as Epeak, is 547 +/- 85 keV.

The event fluence (10-1000 keV) in this time interval is
(8.09 +/- 0.51)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.7 s in the 10-1000 keV band
is 2.36 +/- 0.17 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
Suraj Poolakkil
Fermi GBM Graduate Research Assistant
Dept. of Space Science
University of Alabama in Huntsville
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