TITLE: GCN CIRCULAR NUMBER: 18664 SUBJECT: GRB 151205A: Fermi GBM detection DATE: 15/12/06 00:08:29 GMT FROM: Matthew Stanbro at UAH/Fermi Matthew Stanbro (UAH) reports on behalf of the Fermi GBM Team: "At 15:46:01.90 UT on 05 December 2015, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 151205A (trigger 471023165 / 151205657) which was also detected by the Swift/BAT (Cummings et al. 2015, GCN 18657). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 76 degrees. The GBM light curve consists of several episodes with a duration (T90) of about 56 s (50-300 keV). The time-averaged spectrum from T0-2.05 s to T0+55.30 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is 1.06 +/- 0.48 and the cutoff energy, parameterized as Epeak, is 153 +/- 12 keV The event fluence (10-1000 keV) in this time interval is (2.56 +/- 0.21)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0-1.34 s in the 10-1000 keV band is 1.36 +/- 0.15 ph/s/cm^2. 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