TITLE: GCN CIRCULAR NUMBER: 32155 SUBJECT: GRB 220528A: Fermi GBM Observation DATE: 22/05/31 15:31:23 GMT FROM: Joe Mangan at UCD J.Mangan (UCD), S. Lesage (UAH) and C.Meegan (UAH) report on behalf of the Fermi GBM Team: "At 06:12:47.41 UT on 28 May 2022, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 220528A (trigger 675411172 / 220528259), which was also detected by the Swift/BAT-GUANO (Raman et al. 2022, GCN 32148 and GCN 32149). The Fermi GBM Final Real-time Localization has been reported in GCN 32147. The GBM light curve consists of a single peak with a duration (T90) of about 0.58 s (50-300 keV). The time-averaged spectrum from T0-0.128 s to T0+0.576 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is 0.08 +/- 0.17 and the cutoff energy, parameterized as Epeak, is 467.5 +/- 50.8 keV The event fluence (10-1000 keV) in this time interval is (1.59 +/- 0.11)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0-0.064 s in the 10-1000 keV band is 4.2 +/- 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/"