TITLE: GCN CIRCULAR NUMBER: 15455 SUBJECT: GRB 131105A: Fermi GBM observation DATE: 13/11/05 16:18:25 GMT FROM: Gerard Fitzpatrick at UCD G. Fitzpatrick (UCD) and P. Jenke (UAH) report on behalf of the Fermi GBM Team: At 02:04:53.49 UT on 05 November 2013, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 131105A (trigger 405309896/131105087), which was also detected by Swift (Cummings et al., GCN 15446) and Konus-Wind (Golenetskii et al, GCN 15452). The GBM on-ground location is consistent with the Swift/XRT position (Osborne et al., GCN 15448). The angle from the Fermi LAT boresight is 37 degrees. The GBM light curve consists of a multiple-peak structure with a duration (T90) of about 112 s (50-300 keV). The time-averaged spectrum from T0-3 s to T0+121 s is adequately fit by a Band function with Epeak = 203.9 +/- 31.1 keV, alpha = -1.2 +/- 0.1, and beta = -1.8 +/- 0.1. The event fluence (10-1000 keV) in this time interval is (2.9 +/- 0.1)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+108 s in the 10-1000 keV band is 8.4 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog.