TITLE: GCN CIRCULAR NUMBER: 9131 SUBJECT: GRB 090411B: Fermi GBM detection DATE: 09/04/16 14:39:32 GMT FROM: Rob Preece at UAH Rob Preece (UAH) reports on behalf of the Fermi GBM Team: "At 23:47:44.88 UT on 11 April 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090411B (trigger 261186466 / 090411991). The on-ground calculated location, using the GBM trigger data, is RA = 37.0, DEC = 3.2 (J2000 degrees, equivalent to 02 h 28 m, 3 d 15 '), with an uncertainty of 2.8 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 111 degrees. The GBM light curve consists of a single spiky outburst with a duration (T90) of about 18.7 s (8-1000 keV). The time-averaged spectrum from T0-2.56 s to T0+20.9 s is adequately fit by a Band function with Epeak = 189 +/- 37 keV, alpha = -0.8 +/- 0.1, and beta = -2.0 +/- 0.2 (chi squared 369 for 325 d.o.f.). The event fluence (8-1000 keV) in this time interval is (8.0 +/- 0.8)E-6 erg/cm^2. The 0.256-sec peak photon flux measured starting from T0+6.15 s in the 8-1000 keV band is 7.4 +/- 3.0 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."