TITLE: GCN CIRCULAR NUMBER: 9650 SUBJECT: GRB 090709B: Fermi GBM detection DATE: 09/07/10 15:53:17 GMT FROM: Charles Meegan at NASA/MSFC C. Meegan (USRA) and A. J. van der Horst (NASA/MSFC/ORAU) report on behalf of the Fermi GBM Team: "At 15:07:41.14 UT on 09 July 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090709B (trigger 268844863 / 090709630), which was also detected by the SWIFT-BAT (GCN 9633). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 35 degrees. The GBM light curve consists of two pulses with a duration (T90) of about 32 s (8-1000 keV). The time-averaged spectrum from T0-2.0 s to T0+27.6 s is best fit by a power law function with an exponential high energy cutoff. The power law index is -1.01 +/- 0.16 and the cutoff energy, parameterized as Epeak, is 130 +/- 24 keV (chi squared 354 for 365 d.o.f.). The event fluence (8-1000 keV) in this time interval is (1.3 +/- 0.2)E-6 erg/cm^2. The 1-sec peak photon flux measured starting from T0+2.0 s in the 8-1000 keV band is 2.0 +/- 0.3 ph/s/cm^2. The temporal and spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."