TITLE: GCN CIRCULAR NUMBER: 11311 SUBJECT: GRB 100924A: Fermi GBM observation DATE: 10/09/28 07:11:07 GMT FROM: David Gruber at MPE David Gruber (MPE) reports on behalf of the Fermi GBM Team: "At 03:58:08.32 UT on 24 September 2010, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 100924A (trigger 306993490 / 100924165). which was also detected by the Swift-BAT (Mangano et al. 2010, GCN 11294). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 57 degrees. This burst was also independently detected by INTEGRAL SPI-ACS. The GBM light curve shows a bright initial peak with a duration (T90) of about 9.0 +/- 0.4 s (50-300 keV). Fermi entered the SAA ~ 35 s after the trigger. Thus, the observation of additional emission episodes, as reported in Mangano et al. 2010, GCN 11294, was not possible. The time-averaged spectrum from T0+0.003 s to T0+9.088 s is best fit by a simple power law function with index -1.59 +0.02/-0.02 (Castor C-STAT 1767 for 725 d.o.f.). The event fluence (10-1000 keV) in this time interval is (3.33 +/- 0.04)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.384 s in the 10-1000 keV band is 7.3 +/- 0.2 ph/s/cm^2.