TITLE: GCN CIRCULAR NUMBER: 8316 SUBJECT: GRB 080928: Fermi GBM detection DATE: 08/10/03 16:17:37 GMT FROM: Bill Paciesas at UAH Bill Paciesas, Michael Briggs and Rob Preece (UAH), report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 15:04:56 UT on 28 September 2008, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 080928 (trigger 244307097 / 080928.628), which had triggered the Swift BAT ~204 s earlier (Sakamoto et al. GCN 8292). The on-ground calculated location, using the GBM trigger data, is RA = 93.9, Dec = -53.1 (+/- 4.9)(J2000 degrees), with an uncertainty of 4.9 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees), consistent with the Swift location (Sakamoto et al. GCN 8292; Osborne et al. 8295). The emission detected by GBM lasted about 87 s with the strongest emission in the first 20 s, and is approximately coincident with the main emission detected by Swift (Cummings et al. GCN 8294). The time-averaged spectrum from T-5 to T+24 s can be fit by a power-law with an index of -1.80 +/- 0.08. The fluence between 50 and 300 keV over these 87 seconds is (1.5 +/- .1) x 10^-6 erg/cm^2. The spectral analysis results presented above are preliminary; the final results will be published in the GBM GRB Catalog."