GCN Circular 13951
Subject
GRB 121031A: Fermi GBM detection
Date
2012-11-07T03:29:06Z (12 years ago)
From
Adam Goldstein at Fermi-GBM/UAH <adam.m.goldstein@msfc.nasa.gov>
A. Goldstein (UAH) and C.A. Meegan (USRA) report on behalf of the Fermi GBM Team:
"At 22:47:15.27 UT on 31 October 2012, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 121031A (trigger 373416438 / 121031949).
which was also detected by the Swift/BAT (V. D'Elia et al. 2012, GCN 13934).
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is 85 degrees.
This burst was also independently detected by INTEGRAL SPI-ACS.
The GBM light curve consists of two main pulses separated by a
long quiescent period with a total burst duration (T90) of about
242 s (50-300 keV) with a possible soft tail out to about T0+500 s.
The time-averaged spectrum from T0=-47 s to T0+297 s is adequately fit
by a power law function with an exponential high-energy cutoff. The
power law index is -0.87 +/- 0.07 and the cutoff energy, parameterized a
as Epeak, is 142.3 +/- 10.8 keV
The event fluence (10-1000 keV) in this time interval is
(1.99 +/- 0.09)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+4.6 s in the 8-1000 keV band is 7.4 +/- 0.7 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."