GCN Circular 32241
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/"