[vsnet-grb-info 18994] GRB 170126A: Fermi GBM observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20533
SUBJECT: GRB 170126A: Fermi GBM observation
DATE:    17/01/26 19:00:13 GMT
FROM:    Elisabetta Bissaldi at U.Innsbruk/IAPP  <Elisabetta.Bissaldi at uibk.ac.at>

E. Bissaldi (Politecnico & INFN Bari)
reports on behalf of the Fermi GBM Team:


"At 11:30:41.54 UT on 26 January 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170126A (trigger 507123046 / 170126480),
which was also detected by the Swift/BAT (Kocevski et al. 2017, GCN 20530).
The GBM on-ground location is consistent with the Swift position.

The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high peak flux
of the GRB. This ARR was accepted and the spacecraft slewed
to the GBM in-flight location. The initial angle from the
Fermi-LAT boresight to the BAT location is 46 degrees.

The GBM light curve consists of a single peak
with a duration (T90) of about 14 s (50-300 keV).
The time-averaged spectrum from T0 to T0+14 s is
adequately fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.13 +/- 0.04 and
the cutoff energy, parameterized as Epeak, is 260 +/- 21 keV.
A Band function fits the spectrum equally well
with Epeak = 187 +/- 23 keV, alpha = -1.02 +/- 0.06 and
beta = -2.08 +/- 0.11.

The event fluence (10-1000 keV) in this time interval is
(9.5 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1 s in the 10-1000 keV band
is 12.3 +/- 0.4 ph/s/cm^2.


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