TITLE: GCN CIRCULAR NUMBER: 13773 SUBJECT: GRB 120913B: Fermi GBM observation DATE: 12/09/15 02:44:26 GMT FROM: Veronique Pelassa at UAH V. Pelassa (UAH) reports on behalf of the Fermi GBM Team: "At 23:55:58.77 UT on 13 september 2012, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 120913B (trigger 369273361 / 120913997), which was also detected by the Swift/BAT (E.A. Helder et al. 2008, GCN 13763) The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 66 degrees. The GBM light curve consists of 2 peaks at T0-10 and T0+30s on top of a longer plateau, with a duration (T90) of about 110 s (50-300 keV). The time-averaged spectrum from T0-40.961 s to T0+98.306 s is best fit by a Band function with Epeak = 163 +/- 23 keV, alpha = -1.19 +/- 0.06, and beta = -1.97 +/- 0.07 (Cstat 604 for 483 d.o.f.). The event fluence (10-1000 keV) in this time interval is (2.9 +/- 0.7)E-05 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0+37.632 s in the 10-1000 keV band is 5.0 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."