TITLE: GCN CIRCULAR NUMBER: 23352 SUBJECT: GRB 181020A: Fermi GBM detection DATE: 18/10/21 04:22:04 GMT FROM: Peter Veres at UAH P. Veres (UAH) reports on behalf of the Fermi GBM Team: "At 19:00:33.30 UT on 20 October 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 181020A (trigger 561754838 / 181020792). which was also detected by Fermi/LAT (Axelsson GCN 23350) and Swift/BAT (Moss et al., GCN 23349). The GBM on-ground location 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 bright pulse with a duration (T90) of about 15 s (50-300 keV). The time-averaged spectrum from T0-2 s to T0+20.5 s is best fit by a Band function with Epeak = 367 +/- 17 keV, alpha = -0.70 +/- 0.02, and beta = -2.06 +/- 0.07. The event fluence (10-1000 keV) in this time interval is (3.07 +/- 0.04)E-5 erg/cm^2. The 1-sec peak photon flux measured starting from T0+7.4 s in the 10-1000 keV band is 16.6 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."