TITLE:   GCN CIRCULAR
NUMBER:  21491
SUBJECT: GRB 170813A: Fermi GBM observation
DATE:    17/08/15 21:25:46 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076@uah.edu>

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
degrees.

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