TITLE: GCN CIRCULAR NUMBER: 19889 SUBJECT: GRB 160905A: Fermi GBM observation DATE: 16/09/05 18:51:54 GMT FROM: Elisabetta Bissaldi at U.Innsbruk/IAPP E. Bissaldi (Politcenico & INFN Bari) reports on behalf of the Fermi GBM Team: "At 11:18:55.91 UT on 5 September 2016, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 160905A (trigger 494767139 / 160905471), which was also detected by the Swift/BAT (D'Avanzo et al. 2016, GCN 19887). The GBM on-ground location is consistent with the Swift position. The trigger resulted in an Autonomous Repoint Request (ARR) by the GBM Flight Software owing to the high peak flux of the GRB. This ARR was accepted and the spacecraft slewed to the GBM in-flight location. The initial angle from the Fermi LAT boresight to the GBM ground location is 18 degrees. The GBM light curve consists of two peaks with a duration (T90) of about 34 s (50-300 keV). The time-averaged spectrum from T0 to T0+40 s is adequately fit by a Band function with Epeak = 830 ± 30 keV, alpha = -0.77 ± 0.01, and beta = -2.43 ± 0.09. The event fluence (10-1000 keV) in this time interval is (9.0 ± 0.1)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+20 s in the 10-1000 keV band is 16.2 ± 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."