GCN Circular 22138
Subject
GRB 171120A: Fermi GBM Detection
Date
2017-11-21T00:44:27Z (6 years ago)
From
Matthew Stanbro at UAH/Fermi <mcs0001@uah.edu>
M. Stanbro, C. Meegan, (UAH) and A von Kienlin (MPE)
report on behalf of the Fermi GBM Team:
"At 13:20:02.37 UT on 20 November 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 171120A (trigger 532876807 / 171120556)
which was also detected by the Swift/BAT (A. Tohuvavohu et al. 2017, GCN
22133)
and Fermi LAT (F. Longo et al. 2017, GCN 22136).
The GBM on-ground location is consistent with the Swift 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 GBM light curve consists of 2 pulses
with a duration (T90) of about 44 s (50-300 keV).
The time-averaged spectrum from T0+0.002 s to T0+44.897 s is
best fit by a Band function with Epeak = 141 +/- 12 keV,
alpha = -0.91 +/- 0.06, and beta = -2.16 +/- 0.09.
The event fluence (10-1000 keV) in this time interval is
(1.80 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.10 s in the 10-1000 keV band
is 35.69 +/- 0.51 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."