GCN Circular 9962
Arne Rau (MPE) report on behalf of the Fermi GBM Team: "At 04:33:03.97 UT on 29 September 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090929A (trigger 275891585 / 090929190). The on-ground calculated location, using the GBM trigger data, is RA = 51.7, DEC = -7.3 (J2000 degrees, equivalent to 03h 27m, -07d 18'), with an uncertainty of 1.3 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 122 degrees. This burst was also independently detected by INTEGRAL SPI-ACS. The GBM light curve consists of multiple short peaks with a duration (T90) of about 8.5 +/- 0.4 s (8-1000 keV). The time-averaged spectrum from T0+0.002s to T0+4.896s is best fit by a power law function with an exponential high energy cutoff. The power law index is -0.52 +/- 0.06 and the cutoff energy, parameterized as Epeak, is 610.9 +/- 44.5 keV (chi squared 439 for 393 d.o.f.). The event fluence (8-1000 keV) in this time interval is (1.06 +/- 0.03)E-05 erg/cm^2. The 1.822-sec peak photon flux measured starting from T0+0.002 s in the 8-1000 keV band is 10.9 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."