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GCN Circular 21992

GRB 171010A: Fermi GBM observation
2017-10-11T16:33:18Z (7 years ago)
Suraj Poolakkil at UAH <>
S. Poolakkil and C. Meegan (UAH) report on behalf of the Fermi GBM Team:

"At 19:00:50.58 UT on 10 October 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 171010A (trigger 529354855 / 171010792)
which was also detected by Fermi LAT (N. Omodei et al. 2017, GCN 21985) and
AstroSat (Sharma et al, GCN 21990). The afterglow was observed by Swift-XRT
(A. D'Ai  et al. 2017, GCN 21989). The GBM on-ground location is consistent
the 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 best location is 113 degrees.

The GBM light curve consists of several episodes
with a duration (T90) of about 104 s (50-300 keV).
The time-averaged spectrum from T0+5.12 s to T0+151.55 s is
best fit by a Band function with Epeak = 154 +/- 1 keV, alpha = -1.11 +/-
and beta = -2.22 +/- 0.01.

The event fluence (10-1000 keV) in this time interval is
6.42E-04 +/- 1.5E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+68.16 s in the 10-1000 keV band
is 117.5 +/- 1.02 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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