TITLE: GCN CIRCULAR NUMBER: 10397 SUBJECT: GRB 100205B: Fermi GBM detection DATE: 10/02/07 18:20:33 GMT FROM: David Gruber at MPE David Gruber (MPE) reports on behalf of the Fermi GBM Team: "At 11:45:38.26 UT on 05 February 2010, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 100205B (trigger 287063140 / 100205490). The on-ground calculated location, using the GBM trigger data, is RA = 133.9, DEC = -23.0 (J2000 degrees, equivalent to 08h 55m, 23d 00'), with an uncertainty of 8.2 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 pulse with a duration (T90) of about 13.6 +/- 1.6s (8-1000 keV). The time-averaged spectrum from T0-1.024s to T0+7.168 s is best fit by a power law function with an exponential high energy cutoff. The power law index is -0.47 (+0.20/-0.19) and the cutoff energy, parameterized as Epeak, is 124.20 (+16.0/-12.2)keV (c-stat 468.61 for 349 d.o.f.). The event fluence (8-1000 keV) in this time interval is (1.410 +/- 0.082)E-6 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0 in the 8-1000 keV band is 2.98 +/- 0.22 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."