GCN Circular 35360

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

"At 20:24:24.68 UT on 14 December 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 231214A (trigger 724278269 / 231214850),
which was also detected by the Swift/BAT (Brivio et al. 2023, GCN 35335
Not found
 
 
),
Fermi-LAT (Kocevski et al. 2023, GCN 35342
Not found
 
 
) and AstroSat CZTI (Navaneeth et al. 
GCN 35348
Not found
 
 
). The Fermi GBM Final Real-time Localization (GCN 35334
Not found
 
 
) is consistent
with the Swift position. 

The angle from the Fermi LAT boresight at the GBM trigger time is 50.0 degrees.

The GBM light curve consists of two distinct peaks
with a duration (T90) of about 21 s (50-300 keV).
The time-averaged spectrum from T0-0.5 s to T0+26.1 s is
best fit by a Band function with Epeak = 142.5 +/- 5 keV,
alpha = -0.46 +/- 0.05, and beta = -2.5 +/- 0.1.

The event fluence (10-1000 keV) in this time interval is
(2.25 +/- 0.05)E-5 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+16.12 s in the 10-1000 keV band
is 22.24 +/- 1.77 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/"