TITLE:   GCN CIRCULAR
NUMBER:  35955
SUBJECT: GRB 240317B: Fermi GBM Observation
DATE:    24/03/18 16:26:15 GMT
FROM:    rachel.hamburg@ijclab.in2p3.fr

R. Hamburg (CNRS/IN2P3/IJCLab) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 10:54:24.02 UT on 17 March 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 240317B (trigger 732365669/240317454),
which was also detected by Swift/BAT-GUANO (DeLaunay et al. 2024, GCN 35948).
The Fermi GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight is 89 degrees.

The GBM light curve shows one main emission episode with a duration (T90)
of about 35 s (50-300 keV). The time-averaged spectrum
from T0-6.1 to T0+32.8 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.6 +/- 0.3 and the cutoff energy,
parameterized as Epeak, is 76 +/- 9 keV.

The event fluence (10-1000 keV) in this time interval is
(1.9 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+3.0 s in the 10-1000 keV band is 2.3 +/- 0.4 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/"