TITLE: GCN CIRCULAR NUMBER: 32533 SUBJECT: GRB 220907A: Fermi GBM observation DATE: 22/09/08 14:27:54 GMT FROM: Peter Veres at UAH S. Dalessi, C. Meegan and P. Veres (all UAH) report on behalf of the Fermi GBM Team: "At 14:05:26.48 UT on 07 September 2022, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 220907A (trigger 684252331 / 220907587), which was also detected by the Swift/BAT (Page et al. 2022, GCN 32526, 32530). The Fermi GBM Final Real-time Localization (GCN 32525) is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 50 degrees. The GBM light curve shows a single peak with a duration (T90) of about 9 s (50-300 keV). The time-averaged spectrum from T0-2.8 s to T0+5.4 s is best fit by a power law function with index = -1.48 +/- 0.07. The event fluence (10-1000 keV) in this time interval is (1.13 +/- 0.12)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+1.02 s in the 10-1000 keV band is 2.32 +/- 0.24 ph/s/cm^2. A power law function with an exponential high-energy cutoff fits the spectrum equally well. The power law index is -1.01 +/- 0.29 and the cutoff energy, parameterized as Epeak, is 320 +/- 170 keV and fluence (1.02 +/-0.22)E-6 erg/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/"