TITLE: GCN CIRCULAR NUMBER: 8640 SUBJECT: GRB 081206: Fermi GBM detection DATE: 08/12/08 16:10:09 GMT FROM: Andreas von Kienlin at MPE A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team: "At 06:35:53.02 UT on 06 December 2008, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 081206 (trigger 250238154 / 081206275). The on-ground calculated location, using the GBM trigger data, is RA = 120.1, DEC = 32.7 (J2000 degrees, equivalent to 08h 00m, 32d 42'), with an uncertainty of 5.2 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 102 degrees. The GBM light curve consists of a single peak with a duration (T90) of about 24 s (8-1000 keV). The time-averaged spectrum from T0-6.144 s to T0+15.360 s is well fit by a power law function with an exponential high energy cutoff. The power law index is -0.11 +/- 0.24 and the cutoff energy, parameterized as Epeak, is 180 +/- 23 keV (chi squared 245 for 236 d.o.f.). The event fluence (8-1000 keV) in this time interval is (4.0 +/- 0.6)E-06 erg/cm^2. The 1-sec photon flux measured starting from T0+3.072 s in the 8-1000 keV band is 2.4 +/- 0.3 ph/s/cm^2. A Band function fits the spectrum equally well (chi squared 242 for 235 d.o.f.) with Epeak= 151 +/- 29 keV, alpha = 0.13 +/- 0.37 and beta = -2.2 +/- 0.4. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."