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GCN Circular 32511

GRB 220831A: Fermi GBM observation
2022-09-01T17:55:47Z (2 years ago)
Joshua Wood at MSFC/Fermi-GBM <>
J. Wood (NASA/MSFC) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 13:56:32.93 UT on 31 Aug 2022, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 220831A (trigger 683646997 / 220831581).
which was also detected by the Swift/BAT-GUANO (A. Tohuvavohu et al. 2022, GCN 32506)
The GBM on-ground location is consistent with the Swift position.

The on-ground calculated location, using the GBM trigger
data, is RA = 28.1, DEC = -45.1 (J2000 degrees,
equivalent to 01h 52m, -45d 06'), with an uncertainty
of 7.9 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32]).

The angle from the Fermi LAT boresight is 102.0 degrees.

The GBM light curve consists of a single pulse
with a duration (T90) of about 1.7 s (50-300 keV).
The time-averaged spectrum from T0-0.5 s to T0+1.3 s is
best fit by a Band function with Epeak = 46 +/- 8 keV,
alpha = -0.67 +/- 0.45, and beta = -2.7 +/- 0.4

The event fluence (10-1000 keV) in this time interval is
(5.0 +/- 0.5)E-07 erg/cm^2. The 64-ms peak photon flux measured
starting from T0-0.2 s in the 10-1000 keV band
is 9.4 +/- 1.7 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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