TITLE: GCN CIRCULAR NUMBER: 32224 SUBJECT: GRB 220617A: Fermi GBM observation DATE: 22/06/19 01:54:39 GMT FROM: Joshua Wood at MSFC/Fermi-GBM J. Wood (NASA/MSFC) reports on behalf of the Fermi GBM Team: "At 18:31:12.89 UT on 17 June 2022, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 220617A (trigger 677183477 / 220617772). which was also detected by the Fermi-LAT (N. Di Lalla et al. 2022, GCN 32212). The Fermi GBM Final Real-time Localization (GCN 32209) is consistent with the LAT position. The GBM light curve consists of a single pulse with a duration (T90) of about 0.7 s (50-300 keV). The time-averaged spectrum from T0-0.1 s to T0+0.5 s is well fit by a power law function with an exponential high-energy cutoff. The power law index is -0.7 +/- 0.1 and the cutoff energy, parameterized as Epeak, is 2.3 +/- 0.3 MeV. The event fluence (10-1000 keV) in this time interval is (2.3 +/- 0.1)E-06 erg/cm^2. The 64-ms peak photon flux measured starting from T0+0.2 s in the 10-1000 keV band is 10 +/- 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/"