TITLE:   GCN CIRCULAR
NUMBER:  36903
SUBJECT: GRB 240718A: Fermi GBM Observation
DATE:    24/07/18 17:41:09 GMT
FROM:    Cuán de Barra at UCD <cuan.debarra@ucdconnect.ie>

C. de Barra (UCD) and C. Meegan (UAH) reports on behalf of the Fermi Gamma-ray Burst Monitor Team:

"At 06:29:00.43 UT on 18 July 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 240718A (trigger 742976945/240718270), which was also detected by Fermi-LAT (Depalo et al. 2024, GCN 36901), SPI-ACS, and SVOM/GRM (SVOM/GRM Team 2024, GCN 36900).
The Final Real-time Localization was reported previously (Fermi GBM Team 2024, GCN 36898).The Fermi GBM on-ground location is consistent with the Fermi-LAT position.

The angle from the Fermi LAT boresight is 52 degrees.

The GBM light curve consists of multiple peaks with a duration (T90)
of about 59 s (50-300 keV). The time-averaged spectrum
from T0-2.7 to T0+59.8 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.00 +/- 0.01 and the cutoff energy,
parameterized as Epeak, is 1626 +/- 106 keV.

The event fluence (10-1000 keV) in this time interval is
(5.81 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.26 s in the 10-1000 keV band is 29.9 +/- 0.5 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/"