TITLE: GCN CIRCULAR NUMBER: 26000 SUBJECT: GRB 191011A: Fermi GBM observation DATE: 19/10/11 14:23:34 GMT FROM: Peter Veres at UAH E. Bissaldi (Politecnico and INFN Bari) and P. Veres (UAH) report on behalf of the Fermi GBM Team: "At 04:35:58.58 UT on 11 October 2019, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 191011A (trigger 592461363 / 191011192), which was also detected by the Swift/BAT (Laha et al. 2019, GCN 25988). The GBM localization statistic exhibited two minima, one of which is consistent with the Swift location (75% containment). The localization centroid in the Real-time Localization notice (GCN 25987) is for the other minimum, which is near the Earth limb and is inconsistent with the Swift location. The angle from the Fermi LAT boresight at the GBM trigger time is 39 degrees. The GBM light curve shows several pulses with a duration (T90) of about 13 s (50-300 keV). The time-averaged spectrum from T0-2.0 s to T0-0.38 s is adequately fit by a simple power law function with index -1.76 +/- 0.08. The event fluence (10-1000 keV) in this time interval is (4.33 +/- 0.50)E-7 erg/cm^2. The 1-sec peak photon flux measured starting from T0-1.8 s in the 10-1000 keV band is 3.29 +/- 0.30 ph/s/cm^2. A power law function with an exponential high-energy cutoff fits the spectrum equally well. The power law index is -1.24 +/- 0.29 and the cutoff energy, parameterized as Epeak, is 89 +/- 23 keV. 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/"