TITLE: GCN CIRCULAR NUMBER: 19869 SUBJECT: GRB 160820A: Fermi GBM observation DATE: 16/08/26 16:27:47 GMT FROM: Hoi-Fung Yu at MPE H.-F. Yu (MPE) and C.A. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 11:54:10.65 UT on 20 August 2016, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 160820A (trigger 493386854 / 160820496), which was also detected by the Konus-Wind (Svinkin et al., GCN 19851) and located by the Interplanetary Network (Svinkin et al., GCN 19850). The GBM on-ground location is consistent with the IPN position. The angle from the Fermi LAT boresight at the GBM trigger time is 63 degrees. The GBM light curve shows a single pulse with a duration (T90) of about 0.4 s (50-300 keV). The time-averaged spectrum from T0-0.064 s to T0+0.192 s is best fit by a Band function with Epeak = 810 +/- 200 keV, alpha = -0.7 +/- 0.1, and beta = -2.6 +/- 0.8. The event fluence (10-1000 keV) in this time interval is (7.7 +/- 0.4)E-07 erg/cm^2. The 64-ms peak photon flux measured starting from T0+0.000 s in the 10-1000 keV band is 13 +/- 1 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."