GCN Circular 35488

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


"At 12:57:23.76 UT on 01 January 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 240101C (trigger 725806648/240101540),
which was also detected by the Swift/BAT-GUANO (J. DeLaunay et. al. 2023, GCN 35482
Not found
 
 
), 
GRBAlpha (Dafcikova et al. GCN Circ. 35459
Not found
 
 
) and AstroSat CZTI (Navaneeth et al. 
GCN 35478
Not found
 
 
). The Fermi GBM on-ground calculated location, using the Fermi GBM 
trigger data has been reported at GCN 35451
Not found
 
 
.

The angle from the Fermi LAT boresight at the GBM trigger time is 69.0 degrees.

The GBM light curve consists of one very short peak
with a duration (T90) of about 0.35 s (50-300 keV).
The time-averaged spectrum from T0-0.064 s to T0+0.256 s is
best fit by a Comptonized Epeak function with Epeak = 286.4 +/- 21.8 keV, and
alpha = 0.10 +/- 0.14.

The event fluence (10-1000 keV) in this time interval is
(1.19 +/- 0.07)E-6 erg/cm^2. The 64-msec peak photon flux measured
starting from T0 in the 10-1000 keV band
is 460.9 +/- 77.4 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak= 242.7 +/- 28.8 keV, alpha = 0.30 +/- 0.20 and beta = -2.50 +/- 0.39.

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/"