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GCN Circular 28362

GRB 200903A: Fermi GBM detection
2020-09-04T00:48:15Z (4 years ago)
Stephen Lesage at Fermi-GBM Team <>
S. Lesage (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 00:44:19.25 UT on 3 September 2020, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 200903A (trigger 620786664 / 200903031)
which was also detected by the Swift/BAT (A. P. Beardmore et al. 2020, GCN
The Fermi GBM Final Real-time Localization (GCN 28349) is consistent with
the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is ~61

The GBM light curve shows a single bright peak
with a duration (T90) of about 26.9 s (50-300 keV).
The time-averaged spectrum from T0-5.4 s to T0+21.5 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.9 +/- 0.1 and
the cutoff energy, parameterized as Epeak, is 111.4 +/- 8.9 keV.

The event fluence (10-1000 keV) in this time interval is
(4.6 +/- 0.2)E-06 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+3.3 s in the 10-1000 keV band
is 6.03 +/- 0.24 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
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