GCN Circular 16850
A. von Kienlin (MPE) and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 10:29:53.55 UT on 28 September 2014, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 140928A (trigger 433592996 / 140928437) which was also detected by Fermi/LAT (Desiante et al. 2014, GCN 16847) and Swift (Pagani et al. 2014, GCN 16848). The GBM on-ground location is consistent with the LAT/Swift position. The angle from the Fermi LAT boresight is 110 degrees. This burst was also independently detected by INTEGRAL SPI-ACS. The GBM light curve shows a structured pulse with a duration (T90) of about 14 s (50-300 keV). The time-averaged spectrum from T0-3.072 s to T0+8.192 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.12 +/- 0.13 and the cutoff energy, parameterized as Epeak, is 732 +/- 72 keV. The event fluence (10-1000 keV) in this time interval is 1.02 +/- 0.04)E-05 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0+5.12 s in the 10-1000 keV band is 4.8 +/- 0.3 ph/s/cm^2. A Band function fits the spectrum equally well with Epeak= 671 +/- 82 keV, alpha = -0.05 (+0.16/-0.13) and beta = -2.6 (+0.3/-0.4). The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."