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GCN Circular 32241

Subject
GRB 220618A: Fermi GBM detection
Date
2022-06-21T16:48:36Z (2 years ago)
From
Suraj Poolakkil at UAH <sp0076@uah.edu>
S. Poolakkil (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 09:10:19.59 UT on 18 June 2022, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 220618A (trigger 677236224 / 220618382)
which was also detected by the Swift/BAT (Troja et al. 2022, GCN 32214).

The angle from the Fermi LAT boresight at the GBM trigger time is 35
degrees.

The GBM light curve consists of a single peak followed
by some extended emission with a duration (T90) of about 44 s (50-300 keV).
The time-averaged spectrum from T0-4.096 s to T0+24.576 s
is best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.30 +/- 0.13  and
the cutoff energy, parameterized as Epeak, is 126 +/- 8 keV.

The event fluence (10-1000 keV) in this time interval is
(3.6 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+10.05 s in the 10-1000 keV band
is 2.3 +/- 0.2 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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