TITLE: GCN CIRCULAR NUMBER: 10345 SUBJECT: GRB 100117A: Fermi GBM detection DATE: 10/01/18 19:14:16 GMT FROM: Bill Paciesas at UAH W. Paciesas (UAH) reports on behalf of the Fermi GBM Team: "At 21:06:19.66 UT on 17 January 2010, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 100117A (trigger 285455181 / 100117879) which was also detected by the Swift-BAT (De Pasquale et al. 2010, GCN 10336). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 86 degrees. The GBM light curve consists of one pulse with a duration (T90) of about 0.4 s. The time-averaged spectrum from T0-0.128 s to T0+0.256 s is adequately fit by a power law function with an exponential high energy cutoff. The power law index is -0.14 (+0.33 / -0.27) and the cutoff energy, parameterized as Epeak, is 287 (+74 / -50) keV (CSTAT 548 for 484 d.o.f.). The event fluence (8-1000 keV) in this time interval is (4.1 +/- 0.5 )E-07 erg/cm^2. The 0.256-sec peak photon flux measured starting from T0-0.128 s in the 8-1000 keV band is 6.1 +/- 0.4 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."