TITLE: GCN CIRCULAR NUMBER: 8644 SUBJECT: GRB 081206C: Fermi GBM detection DATE: 08/12/09 21:03:11 GMT FROM: Sylvain Guiriec at UAH S. Guiriec (UAH) and A.J. van der Horst (NASA/MSFC/ORAU) report on behalf of the Fermi GBM Team: "At 23:41:50.47 UT on 6 December 2008, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 081206C (trigger 250299711 / 081206987). The on-ground calculated location, using the GBM trigger data, is RA = 41.12, DEC = -14.42 (J2000 degrees, equivalent to +2h44m, -14d25'), with an uncertainty of 7.7 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 71 degrees. The GBM light curve shows a main pulse of ~20 seconds starting at ~T0-11s. There is additional weak emission up to T0+83s. The time-averaged spectrum from T0-9s to T0+11s is adequately fit by a simple power-law function with index -1.35 +/- 0.04 (chi squared 505 for 481 d.o.f.). The fluence (50-300 keV) in this time interval is (1.19 +/- 0.04)E-6 erg/cm^2. The 1-sec peak photon flux measured starting from T0-1s in the 50-300 keV band is 0.76 +/- 0.04 ph/s-cm^2. The spectral and timing analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."