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GCN Circular 19804

GRB 160816730A: Fermi GBM detection/observation
2016-08-17T00:41:06Z (8 years ago)
Bagrat Mailyan at UAH <>
B. Mailyan (UAH) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:

"At 17:30:57.97 UT on 16 August 2016, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 160816730A (trigger 493061461  / 160816730), which
was also detected by the LAT (Racusin et al., 2016, GCN 19802).
The on-ground calculated location, using the GBM trigger data, is consistent
with LAT position.

The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high peak flux
of the GRB. This ARR was accepted and the spacecraft slewed to the GBM in-flight
location. The initial angle from the Fermi LAT boresight to
the GBM ground location is 34 degrees.

The GBM light curve consists of multiple peaks
with a duration (T90) of about 11.0 s (50-300 keV).
The time-averaged spectrum from T0-0 s to T0+13.8 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.73 +/- 0.02 and
the cutoff energy, parameterized as Epeak, is 235 +/- 4.29  keV.

A Band function fits the spectrum equally well
with Epeak = 224 +/- 5.46 keV, alpha = -0.71 +/- 0.02 and beta = -2.97 +/- 0.19.

The event fluence (10-1000 keV) in this time interval is
(3.467 +/- 0.037)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+7.6 s in the 10-1000 keV band is 39.1 +/- 0.4 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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