[vsnet-grb-info 12382] GRB 120911B: Fermi GBM observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13757
SUBJECT: GRB 120911B: Fermi GBM observation
DATE:    12/09/12 23:37:58 GMT
FROM:    David Gruber at MPE  <dgruber at mpe.mpg.de>

David Gruber (MPE), W. Paciesas (USRA), V. Pélassa (UAH)
and V. Chaplin (UAH) report on behalf of the Fermi GBM Team:

"We report on the ground analysis of the IPN detected GRB 120911B (GCN 13755) 
in the GBM data.

The GBM light curve consists of a precursor starting at ~ 06:25:14 UT (T0) 
which is followed by a bright and hard main emission ~ 50 s later, lasting
for another ~ 40 s.
The duration (T90) is of about 69 s (50-300 keV).
The time-averaged spectrum from T0 to T0+132 s is best fit by a Band function
with Epeak = 1200 +/- 55 keV, alpha = -1.01 +/- 0.01,
and beta = -2.72 +/- 0.14.

The event fluence (10-1000 keV) in this time interval is
(1.973 +/- 0.026)E-04 erg/cm^2. The 4-sec peak photon flux measured
starting from T0+70 s in the 10-1000 keV band
is 33.04 +/- 0.7 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."