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GCN Circular 34950

GRB 231104A: Fermi GBM Observation
2023-11-05T05:31:07Z (7 months ago)
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S. Bala (USRA) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 01:47:28.14 UT on 04 November 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 231104A (trigger 720755253/231104075).
which was also detected by Swift BAT (K. L. Page et al. 2023, GCN 34938) and 
Fermi LAT (G. Principe. et al. 2023, GCN 34943).
The Fermi GBM on-ground location is consistent with the Swift BAT position.

The angle from the Fermi LAT boresight is 32 degrees.

The GBM light curve Consist of three distinguishable pick with a duration (T90)
of about 44 s (50-300 keV). The time-averaged spectrum
from T0-3.6 to T0+62.0 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.07 +/- 0.01 and the cutoff energy,
parameterized as Epeak, is 539 +/- 22 keV.

The event fluence (10-1000 keV) in this time interval is
(5.59 +/- 0.06)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+3.6 s in the 10-1000 keV band is 2 +/- 0.2 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak= 490 +/- 20 keV, alpha = -1.05 +/- 0.02 and beta = -2.6 +/- 0.2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:"
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