GCN Circular 31506
Cori Fletcher (USRA) and C. Meegan (UAH) and Boyan A. Hristov (UAH) report on behalf of the Fermi GBM Team: "At 18:20:35.84 UT on 18 January 2022, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 220118A (trigger 664222840 / 220118764), which was also detected by the Swift BAT/XRT (N. J. Klingler et al. 2022, GCN 31490) and observed by SWIFT UVOT (A. Belles et al. 2022, GCN 31498). The Fermi GBM Final Real-time Localization (GCN 31489) is consistent with the Swift position. The GBM light curve shows a single peak with a duration (T90) of about 19 s (50-300 keV). The time-averaged spectrum from T0+0.003 s to T0+18.176 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.08 +/- 0.09 and the cutoff energy, parameterized as Epeak, is 148.30 +/- 17.50 keV. The event fluence (10-1000 keV) in this time interval is (3.017 +/- 0.182)E-06. The 1-sec peak photon flux measured starting from T0+3.39204 s in the 10-1000 keV band is 4.0 +/- 0.28 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/"