TITLE: GCN CIRCULAR NUMBER: 9845 SUBJECT: GRB 090826: Fermi GBM detection DATE: 09/08/28 20:27:44 GMT FROM: Charles Meegan at NASA/MSFC Charles Meegan (USRA) reports on behalf of the Fermi GBM Team: "At 01:37:31.85 UT on 26 August 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090826 (trigger 272943453 / 090826068). The on-ground calculated location, using the GBM trigger data, is RA = 140.6, DEC = -0.1 (J2000 degrees, equivalent to 09 h 22 m, -0 d 6'), with an uncertainty of 9.7 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). The angle from the Fermi LAT boresight is 35 degrees. The GBM light curve consists of two pulses with a duration (T90) of about 8.5 s (8-1000 keV). The time-averaged spectrum from T0-4.096 s to T0+9.216 s is well fit by a power law function with an exponential high energy cutoff. The power law index is -0.96 (+0.32/-0.28) and the cutoff energy, parameterized as Epeak, is 172 (+132/-64) keV (chi squared 232.84 for 241 d.o.f.). The event fluence (8-1000 keV) in this time interval is (1.26 +/- 0.27)E-6 erg/cm^2. The 1-sec peak photon flux measured starting from T0+7.168 s in the 8-1000 keV band is 3.28 +/- 0.35 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."