TITLE:   GCN CIRCULAR
NUMBER:  35205
SUBJECT: GRB 231123C: Fermi GBM Observation
DATE:    23/11/28 00:38:45 GMT
FROM:    Sarah Dalessi at UAH <sd0104@uah.edu>

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

"At 19:58:25.38 UT on 23 November 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 231123C (trigger 722462310/231123832).
which was also detected by Swift/BAT-GUANO (J. DeLaunay et al. 2023, GCN 35179).
The Fermi Final Localization was reported in GCN 35171.

The angle from the Fermi LAT boresight is 90 degrees.

The GBM light curve single peak with a duration (T90)
of about 0.4 s (50-300 keV). The time-averaged spectrum
from T0-0.1 to T0+0.4 s is best fit by
a Power law function with alpha = -1.29 +/- 0.06.

The event fluence (10-1000 keV) in this time interval is
(3.3 +/- 0.4)E-07 erg/cm^2. The 64-ms peak photon flux measured
starting from T0-0.064 s in the 10-1000 keV band is 5 +/- 1 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/"