TITLE: GCN CIRCULAR NUMBER: 23320 SUBJECT: GRB 181010A: Fermi GBM observation DATE: 18/10/10 19:34:51 GMT FROM: Peter Veres at UAH A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team: "At 05:55:59.39 UT on 10 October 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 181010A (trigger 560843764 / 181010247), which was also detected by the Swift/BAT (Melandri et al. 2018, GCN 23309). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 48.1 degrees. The GBM light curve shows two structured pulses followed a weak tail with an overall duration (T90) of about 60 s (50-300 keV). The time-averaged spectrum from T0-0.256s to T0+1.280s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.8 +/- 0.2 and the cutoff energy, parameterized as Epeak, is 280 +/- 80 keV. The event fluence (10-1000 keV) in this time interval is (6.13 +/- 0.98)E-07 erg/cm^2. The 1.024 sec peak photon flux measured starting from T0-0.128 s in the 10-1000 keV band is 3.35 +/- 0.29 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."