TITLE: GCN CIRCULAR NUMBER: 20056 SUBJECT: GRB 161015A: Fermi GBM detection DATE: 16/10/16 04:08:41 GMT FROM: Matthew Stanbro at UAH/Fermi M Stanbro (UAH) and C Meegan (UAH) report on behalf of the Fermi GBM Team: "At 17:03:07.03 UT on 15 October 2016, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 161015A (trigger 498243791 / 161015710), which was also detected by the Fermi-LAT (Masanori Ohno et al. 2016, GCN 20054) The GBM on-ground location is consistent with the Fermi-LAT position. The GBM light curve consists of 3 episodes with a duration (T90) of about 15 s (50-300 keV). The time-averaged spectrum from T0-0.003 s to T0+16.384 s is best fit by a Band function with Epeak = 151 +/- 9 keV, alpha = -0.82 +/- 0.05, and beta = -2.32 +/- 0.11. The event fluence (10-1000 keV) in this time interval is (1.17 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+2.24 s in the 10-1000 keV band is 10.58 +/- 0.30 ph/s/cm^2. A power law function with an exponential high-energy cutoff fits the spectrum equally well with Epeak= 183 +/- 7 keV, alpha = -0.93 +/- 0.03. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." -- Matthew C. Stanbro Fermi GBM Graduate Research Assistant University of Alabama in Huntsville