//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8302 SUBJECT: GRB 080927: Fermi GBM detection DATE: 08/09/30 15:04:40 GMT FROM: Elisabetta Bissaldi at MPE E. Bissaldi, S. McBreen and A. von Kienlin (MPE) report on behalf of the Fermi GBM Team: "At 11:30:32 UT on 27 September 2008, the Fermi Gamma-ray Burst Monitor triggered and located GRB 080927 (trigger 244207833 / 080927480). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 57.8, Dec = +30.0 (equivalent to J2000 03h 51m, 30d 00'), with a statistical uncertainty of 4.0 degrees (radius, 1-sigma containment; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). The angle from the Fermi LAT boresight is 75 degrees. This GRB is singled peaked with an estimated T90 (25-1000 keV) of about 25 s. The time-averaged spectrum from T0-1.3s to T0+20.2s is adequately fit by a simple power law with index -1.5 +/- 0.1. An improvement in the fit is obtained using the Band model with Epeak = 40 +/- 10 keV and beta = -1.7 +/- 0.1. However alpha is poorly constrained. The fluence (25-1000 keV) in this time interval from the power law model is (5.7 +/- 0.2)E-06 erg/cm2. The 1s peak photon flux measured starting from T0+5.9 in the 25-1000 keV band is 2.0 +/- 0.1 ph/s/cm2. The spectral analysis results presented above are preliminary; the final results will be published in the Fermi GBM GRB Catalog."