GCN Circular 9983
Arne Rau (MPE) reports on behalf of the Fermi GBM Team: "At 04:35:45.58 UT on 03 September 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 091003A (trigger 276237347 / 091003191). The on-ground calculated location, using the GBM trigger data, is RA = 251.1, DEC = 37.2 (J2000 degrees, equivalent to 16h 44m, 37d 12'), with an uncertainty of 1.0 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 13 degrees. This burst was also independently detected by INTEGRAL SPI-ACS. The GBM light curve consists of multiple peaks with a duration (T90) of about 21.1 +/- 0.5s (8-1000 keV). The time-averaged spectrum from T0-0.384s to T0+23.168s is best fit by a Band function with Epeak = 486.2 +/- 23.6 keV, alpha = -1.13 +/- 0.01, and beta = -2.64 +/- 0.24 (chi squared 851 for 611 d.o.f.). The event fluence (8-1000 keV) in this time interval is (3.76 +/- 0.04)E-05 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0+18.048 s in the 8-1000 keV band is 31.8 +/- 0.4 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."