GCN Circular 30210
S. Poolakkil (UAH) and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 03:56:02.12 UT on 6 June 2021, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 210606A (trigger 644644567 / 210606164) which was also detected by the Swift/BAT-GUANO (DeLaunay et al. 2021, GCN 30134) The Fermi GBM Final Real-time Localization (GCN 30131) is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 108 degrees. The GBM light curve consists of a single peak followed by some extended emission with a duration (T90) of about 11 s (50-300 keV). The time-averaged spectrum from T0-4.09 s to T0-1.02 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.99 +/- 0.22 and the cutoff energy, parameterized as Epeak, is 195 +/- 62 keV. The event fluence (10-1000 keV) in this time interval is (0.845 +/- 0.144)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0-2.05 s in the 10-1000 keV band is 2.5 +/- 0.3 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/"