TITLE:   GCN CIRCULAR
NUMBER:  35974
SUBJECT: GRB 240318A: Fermi GBM Observation
DATE:    24/03/21 21:31:30 GMT
FROM:    Lorenzo Scotton at UAH <lscottongcn@outlook.com>

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

"At 02:51:01.82 UT on 18 March 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 240318A (trigger 732423066/240318119),
which was also detected by Glowbug (Cheung et al. 2024, GCN 35959) 
and Swift/BAT-GUANO (DeLaunay et al. 2024, GCN 35969).
The Fermi GBM Final Real-time Localization was provided in GCN 35949. 

The angle from the Fermi LAT boresight is 53 degrees.

The GBM light curve consists of a single emission episode with a duration (T90)
of about 8 s (50-300 keV). The time-averaged spectrum
from T0-2.0 to T0+11.0 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.5 +/- 0.2 and the cutoff energy,
parameterized as Epeak, is 112 +/- 8 keV.

The event fluence (10-1000 keV) in this time interval is
(2.1 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.1 s in the 10-1000 keV band is 4.5 +/- 0.3 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/"