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GCN Circular 34899

GRB 231028A: Fermi GBM Detection
2023-10-28T22:45:43Z (8 months ago)
Peter Veres at University of Alabama in Huntsville <>
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P. Veres (UAH) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 04:09:06.66 UT on 28 October 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 231028A (trigger 720158951/231028173),
which was also detected by the Swift/BAT (Williams et al. 2023, GCN 34894).
The Fermi GBM Final Real-time Localization (GCN 34893) is consistent with the Swift position.

The GBM light curve consists of multiple peaks with a duration (T90)
of about 34.8 s (50-300 keV). The time-averaged spectrum
from T0-4.1 to T0+43.0 s is best fit by
a Band function with Epeak = 157 +/- 11 keV,
alpha = -0.72 +/- 0.06, and beta = -2.13 +/- 0.08.

The event fluence (10-1000 keV) in this time interval is
(1.95 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+4.0 s in the 10-1000 keV band is 14.8 +/- 0.4 ph/s/cm^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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