GCN Circular 18756
Subject
GRB 151229A: Fermi GBM observation
Date
2015-12-29T17:07:57Z (8 years ago)
From
Andreas von Kienlin at MPE <azk@mpe.mpg.de>
A. von Kienlin (MPE) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:
"At 06:50:27.95 UT on 29 December 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 151229A (trigger 473064631 / 151229285 ),
which was also detected by the Swift/BAT (Kocevski et al. 2015, GCN 18745)
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 53.4 degrees.
The GBM light curve consists of a single peak
with a duration (T90) of about 3.5 s (50-300 keV).
The time-averaged spectrum from T0-0.256: s to T0+1.280 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.19 (+0.10/-0.09) and
the cutoff energy, parameterized as Epeak, is 97.1 (+10.3/-8.3) keV
The event fluence (10-1000 keV) in this time interval is
(9.4 +/- 0.5)E-07 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0-0.128 s in the 10-1000 keV band
is 11.0 +/- 0.3 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."