GCN Circular 31922

R. Hamburg (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 13:52:35.96 UT on 17 April 2022, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 220417A (trigger 671896360 / 220417578),
which was also detected by the Swift/BAT-GUANO (Raman et al. 2022,
GCN 31918
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 ).

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

The GBM light curve shows a single peak with a duration (T90) of
about 17 s (50-300 keV). The time-averaged spectrum from T0-5.1 s
to T0+5.1 s is adequately fit by a power law function with an
exponential high-energy cutoff.  The power law index is
0.51 +/- 0.57 and the cutoff energy, parameterized as Epeak,
is 431 +/- 97 keV.

The event fluence (10-1000 keV) in this time interval is
(2.5 +/- 0.4)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.3 s in the 10-1000 keV band is 1.3 +/- 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/"