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GCN Circular 13737

GRB 120909A: Fermi GBM observation
2012-09-09T19:49:34Z (12 years ago)
Vandiver Chaplin at UAH/Fermi-GBM <>
V.Chaplin (UAH) reports on behalf of the Fermi GBM Team:

At 01:41:22.40 UT on 09 September 2012, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 120909A (trigger 368847685 / 120909070), 
which was also detected by the Swift/BAT (Immler et al. 2012, GCN 13727)
The GBM on-ground location is consistent with the Swift position.
The angle to the Fermi LAT boresight is 66 degrees.

The GBM light curve consists of several peaks between T0
and T0+100 seconds, with a total duration (T90) of about 
112 s (50-300 keV).

The time-averaged spectrum from T0-2.8 s to T0+104.7 s is
best fit by a power law with exponential cutoff having 
an index of -1.3 +/- 0.1 and cutoff energy 370 +/- 140 keV.
The event fluence (10-1000 keV) in this time interval is
(2.1 +/- 0.2)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+3.26 s in the 10-1000 keV band
is 3.0 +/- 0.2 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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