GCN Circular 33125
Subject
GRB 221226A: Fermi GBM detection
Date
2022-12-30T16:17:59Z (2 years ago)
From
Peter Veres at UAH <veresp@gmail.com>
P. Veres and C. Meegan (both UAH)
report on behalf of the Fermi GBM Team:
"At 16:44:27.06 UT on 26 December 2022, the Fermi Gamma-Ray Burst
Monitor (GBM) triggered and located GRB 221226A (trigger 693765872 /
221226698) which was also detected by the AGILE (Panebianco et al.,
GCN 33113) and Swift/BAT (Raman et al., GCN 33121). The Fermi GBM
Final Real-time Localization was reported in GCN 33104, and it is
consistent with the IPN triangulation (Kozyrev et al., GCN 33123)
The GBM light curve consists of two emission episodes with a duration
(T90) of about 129 s (50-300 keV). The time-averaged spectrum from
T0-3 s to T0+129 s is best fit by a power law function with an
exponential high-energy cutoff. The power law index is -1.18 +/- 0.03
and the cutoff energy, parameterized as Epeak, is 340 +/- 32 keV.
The event fluence (10-1000 keV) in this time interval is (2.98 +/-
0.10)E-5 erg/cm^2. The 1-sec peak photon flux measured starting from
T0+4.8 s in the 10-1000 keV band is 20.7 +/- 0.4 ph/s/cm^2.
A Band function fits the spectrum equally well with Epeak= 229 +/- 35
keV, alpha = -1.10 +/- 0.05 and beta = -1.90 +/- 0.08.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"