GCN Circular 31928
C. Fletcher (USRA), S. Dalessi (UAH) and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 17:16:21.65 UT on 18 April 2022, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 220418B (trigger 671994986 / 220418720). which was also detected by the Swift-BAT/GUANO (GCN 31919, 31921) The Fermi GBM Final Real-time Localization (GCN 31915) is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 80 degrees. The GBM light curve shows a single peak with a duration (T90) of about 1.7 s (50-300 keV). The time-averaged spectrum from T0-1.024 s to T0+1.024 s is best fit a simple power law function with index -1.6 +/- 0.1. The event fluence (10-1000 keV) in this time interval is (3.8 +/- 0.6)E-07 erg/cm^2. The 64-ms peak photon flux measured starting from T0-0.57 s in the 10-1000 keV band is 121 +/- 76 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/"