TITLE: GCN CIRCULAR NUMBER: 31922 SUBJECT: GRB 220417A: Fermi GBM detection DATE: 22/04/19 18:56:31 GMT FROM: Rachel Hamburg at UAH 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). 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/"