GCN Circular 33112
Subject
GRB 221226B: Fermi GBM Observation
Date
2022-12-27T13:16:51Z (a year ago)
From
Rachel Hamburg at UAH <rkh0007@uah.edu>
S. Lesage (UAH) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 22:41:20 UT on 26 December 2022, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 221226B (trigger 693787285/221226945),
which was also detected by Swift BAT (S. B. Cenko et al. 2022, GCN 33108)
and has a measured redshift from the VLT/X-Shooter (GCN 33110). The Fermi
GBM Final Real-time Localization (GCN 33107) is consistent with the Swift
BAT position.
The angle from the Fermi LAT boresight is 58 degrees.
The GBM light curve consists of a single emission episode with a duration
(T90)
of about 5 s (50-300 keV). The time-averaged spectrum
from T0+0.002 to T0+2.592 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is 0.2 +/- 0.2 and the cutoff energy,
parameterized as Epeak, is 104 +/- 8 keV.
The event fluence (10-1000 keV) in this time interval is
(7.8 +/- 0.5)E-07 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.3 s in the 10-1000 keV band is 4.1 +/- 0.2 ph/s/cm^2.
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/"