TITLE: GCN CIRCULAR NUMBER: 10204 SUBJECT: GRB 091127: Fermi GBM detection DATE: 09/11/28 22:01:05 GMT FROM: Colleen A. Wilson at NASA/MSFC/NSSTC Colleen A. Wilson-Hodge (NASA/MSFC) and Robert D. Preece (UAH) report on behalf of the Fermi GBM Team: "At 23:25:45.48 UT on 27 November 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 091127 (trigger 281057147 / 091127976), which was also detected by the SWIFT-BAT (Troja et al. 2009, GCN 10191) The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 25 degrees. The GBM light curve consists of three peaks with a duration (T90) of about 9 s (8-1000 keV). The time-averaged spectrum from T0+0.002 s to T0+9.984 s is adequately fit by a Band function with Epeak = 36 +/- 2 keV, alpha = -1.27 +/- 0.06, and beta = -2.20 +/- 0.02 (chi squared 645.8 for 445 d.o.f.). The event fluence (8-1000 keV) in this time interval is (1.87 +/- 0.02)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+1 s in the 8-1000 keV band is 46.9 +/- 0.9 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."