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GCN Circular 32479

Subject
GRB 220823A: Fermi GBM detection
Date
2022-08-24T16:43:38Z (a year ago)
From
Boyan A. Hristov at UAH <bah0046@uah.edu>
B. Hirstov (UAH) and C. Fletcher (USRA)
report on behalf of the Fermi GBM Team:

"At 03:28:52.39 UT on 23 August 2022, the Fermi Gamma-Ray
Burst Monitor (GBM) triggered and located GRB 220823A
(trigger 682918137 / 220823145),which was also detected by
Swift/BAT-GUANO (A. Tohuvavohu et al. 2022, GCN 32476).

The on-ground calculated location, using the GBM trigger
data, is RA = 82.94, DEC = +2.44 (J2000 degrees, equivalent
to 05h, 31m, 2d 26'), with a statistical uncertainty of 3
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 at the GBM trigger
time is 15 degrees.

The GBM light curve consists of single peak with a duration
(T90) of 1.1 +/- 0.7 s (50-300 keV).

The time-averaged spectrum from T0-1.024 s to T0+0.256 s is
best fit by a power law with an exponential cutoff with
Epeak = 1189 +/- 608 keV and alpha = -0.52 +/- 0.26.

The event fluence (10-1000 keV) in this time interval is
(1.1 +/- 0.1)E-6 erg/cm^2. The 0.064-sec peak photon flux
measured starting from T0-0.064 s in the 10-1000 keV band
is 5 +/- 1 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/"
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