TITLE: GCN CIRCULAR NUMBER: 30738 SUBJECT: GRB 210827A: Fermi GBM Observation DATE: 21/08/28 23:58:01 GMT FROM: Suraj Poolakkil at UAH <sp0076@uah.edu> S. Lesage (UAH), R. Dunwoody (UCD), J. Mangan (UCD) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 09:59:24 UT on 27 August 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210827A (trigger 651751169/210827416) which was also detected by Swift/BAT-GUANO (James DeLaunay et al. 2021, GCN 30732). The Fermi GBM Final Real-time Localization (GCN 30724) is consistent with the Swift/BAT-GUANO position. The angle from the Fermi LAT boresight is 42 degrees. The GBM light curve consists of a single emission episode with a duration (T90) of about 9 s (10-1000 keV). The time-averaged spectrum from T0-2.0 to T0+4.1 s is best fit by a simple power law function with index -1.6 +/- 0.1. The event fluence (10-1000 keV) in this time interval is (7 +/- 1)E-07 erg/cm^2. The 1-sec peak photon flux measured starting from T0-2.5 s in the 10-1000 keV band is 1.7 +/- 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/"