TITLE: GCN CIRCULAR NUMBER: 8798 SUBJECT: GRB 090108: Fermi GBM Detection DATE: 09/01/12 19:00:42 GMT FROM: Adam Goldstein at Fermi-GBM/UAH A. Goldstein (UAH) and R. Preece (UAH) report on behalf of the Fermi GBM Team: "At 00:29:02.37 UT on 08 January 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090108 (trigger 253067344 / 090108020). The on-ground calculated location, using the GBM trigger data, is RA = 263.04, DEC = 52.46 (J2000 degrees, equivalent to 17h 32m, 52d 28'), with an uncertainty of 2.93 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 60 degrees. The GBM light curve consists of a single bright pulse followed by a peak of significantly lesser intensity. The duration of the burst (T90) is about 0.90 s (8-1000 keV). The time-averaged spectrum from T0-0.17 s to T0+0.73 s is best fit by a Band function with Epeak = 104.8 +/- 16.4 keV, alpha = -0.47 +/- 0.20, and beta = -1.97 +/- 0.09 (chi squared 722.8.5 for 733 d.o.f.). The event fluence (8-1000 keV) in this time interval is (1.28 +/- 0.24)E-06 erg/cm^2. The 0.064-sec peak photon flux measured starting from T0+0.027 s in the 8-1000 keV band is 39.7 +/- 3.9 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."