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GCN Circular 15573

Subject
GRB 131126A: Fermi GBM observation
Date
2013-12-04T03:48:52Z (10 years ago)
From
Veronique Pelassa at UAH <vero.pelassa@gmail.com>
V. Pelassa and C. Meegan (UAH) report on behalf of the Fermi GBM Team:

"At 03:54:10.43 UT on 26 November 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 131126A (trigger 407130853 / 131126163)
which was also detected by Konus/Wind (Golenetskii et al 2013, GCN 15551)
leading to an IPN Konus/GBM annulus (Golenetskii et al 2013, GCN 15550).
The angle from the Fermi LAT boresight is 108 degrees.

iPTF also performed a tiled observation of the localization error box and
established an upper limit on the GRB afterglow (Singer et al 2013, GCN 15572).

The GBM light curve consists of a single pulse with a duration (T90)
of about 0.3 s (50-300 keV).

The time-averaged spectrum from T0-0.064 s to T0+0.256 s is
adequately fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.06 +/- 0.13 and
the cutoff energy, parameterized as Epeak, is 600 +/- 62 keV
(Castor statistics 397.51 for 364 d.o.f.).
A Band function fits the spectrum equally well (Castor statistics 391.35
for 363 d.o.f.) with Epeak= 489 +/- 74 keV, alpha = 0.13 +/- 0.20
and beta = -2.29 +/- 0.26.

The event fluence (10-1000 keV) in this time interval is
(2.0 +/- 0.1)E-06 erg/cm^2. The 64-msec peak photon flux measured
starting from T0+0.000 s in the 10-1000 keV band
is 36 +/- 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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