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GCN Circular 35204

Subject

GRB 231123B: Fermi GBM Observation

Event

GRB 231123B

Date

2023-11-27T23:30:13Z (2 years ago)

From

Sarah Dalessi at UAH <sd0104@uah.edu>

Via

Web form

S. Dalessi (UAH), S. Lesage (UAH) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 19:25:21.51 UT on 23 November 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 231123B (trigger 722460326/231123809).
which was also detected by Swift/BAT-GUANO (J. DeLaunay et al. 2023, GCN 35195Loading...
 
 ).
The Fermi Final Localization was reported in GCN 35170Loading...
 
 .

The angle from the Fermi LAT boresight is 104 degrees.

The GBM light curve single peak with a duration (T90)
of about 77 s (50-300 keV). The time-averaged spectrum
from T0+0.003 to T0+76.802 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.2 +/- 0.2 and the cutoff energy,
parameterized as Epeak, is 160 +/- 38 keV.

The event fluence (10-1000 keV) in this time interval is
(5.9 +/- 0.7)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+4.5 s in the 10-1000 keV band is 1.9 +/- 0.3 ph/s/cm^2.

The spectrum is also well fit a Band function with Epeak = 115 +/- 44 keV,
alpha = -1.05 +/- 0.28, and beta = -2.16 +/- 0.31.

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/"