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GCN Circular 13782

Subject
GRB 120916A: Fermi GBM Observation
Date
2012-09-18T16:54:24Z (12 years ago)
From
Gerard Fitzpatrick at UCD <gerard.fitzpatrick@ucdconnect.ie>
G. Fitzpatrick (UCD) reports on behalf of the Fermi GBM Team:

At 04:08:40.75 UT on 16 September 2012, the Fermi Gamma-Ray
Burst Monitor triggered and located GRB 120916A
(trigger 369461323/120916173) which was also detected by
Fermi LAT (G. Vianello et al. GCN 13777), Konus-Wind
(S. Golenetskii et al. GCN 13781) and the IPN (K. Hurley
et al. GCN 13778).

The on-ground calculated location is consistent with the LAT
location.

The GBM light curve consists of 3 peaks with a duration (T90)
of about 53 s (50-300 keV). The last peak is softer and corresponds
to the trigger time, the earlier emission begins at ~T0-60 s.
GBM did not trigger on this earlier emission period owing to the
triggering being disabled while Fermi was passing through a
region of high geomagnetic latitude.

The time-averaged spectrum from T0-53 s to T0+0.2 s is best
fit by a Band function with Epeak = 312.40 (+51.30/-47.20)
keV, alpha = -0.99 (+0.06/-0.06), and beta = -1.90 (+0.09/-0.12).

The event fluence (10-1000 keV) in this time interval is
(1.95 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux
measured starting from T0+-30.7205 s in the 10-1000 keV
band is 9.72 +/- 0.28 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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