[vsnet-grb-info 12587] GRB 121031A: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13951
SUBJECT: GRB 121031A: Fermi GBM detection
DATE:    12/11/07 03:29:06 GMT
FROM:    Adam Goldstein at Fermi-GBM/UAH  <adam.m.goldstein at 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."