GCN Circular 14102
Subject
GRB 121225B: Fermi GBM observation
Date
2012-12-25T18:11:28Z (12 years ago)
From
Michael S. Briggs at UAH and MSFC <michael.briggs@nasa.gov>
D. Tierney (UCD) reports on behalf of the Fermi GBM Team:
"At 10:00:53.58 UT on 25 December 2012, the Fermi Gamma-Ray Burst
Monitor triggered and located GRB 121225B (trigger 378122456 /
121225417). This GRB was also detected by the Fermi LAT (GCN 14101,
Kocevski et al.)
The on-ground calculated location, using the GBM trigger data, is RA =
310.45, DEC = -34.83 (J2000 degrees, equivalent to 20 h 41 m, -34 d 49'),
with an uncertainty of 1.5 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic error which is
currently estimated to be 2 to 3 degrees).
The angle from the Fermi LAT boresight is 66 degrees.
The GBM light curve has a multi-pulse time history with with the main
emission complexes at 15 to 25 seconds and at 45 to 65 seconds. The
duration (T90) is 58.5 +/- 0.8 s (50-300 keV). The time-averaged
spectrum from T0-1.8 s to T0+73.0 s is best fit by a Band function
with Epeak = 277.6 (+13.1/-12.4) keV, alpha = -1.08 (+0.02/-0.02), and
beta = -2.14 (+0.05/-0.06).
The event fluence (10-1000 keV) in this time interval is (7.16 +/-
0.07)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from
T0+22.0 s in the 10-1000 keV band is 23.6 +/- 0.4 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final
results will be published in the GBM GRB Catalog."