TITLE: GCN CIRCULAR NUMBER: 8821 SUBJECT: GRB 090117 - Fermi GBM Observations DATE: 09/01/18 05:58:26 GMT FROM: Valerie Connaughton at MSFC Valerie Connaughton (UAH) reports on behalf of the Fermi GBM Team: "At 15:22:01.05 UT on 17 Jan 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090117 (trigger 253898523 / 090117640) which was also detected by SuperAGILE (Donnarumma et al. 2009, GCN 8817). The GBM on-ground location is consistent with the reported position from SuperAGILE. The angle from the Fermi LAT boresight is 51 degrees. The GBM light curve shows a soft event with a single peak lasting about 2 seconds superimposed on a lower-level continuum. The burst duration (T90) is about 21 s (8-1000 keV). The time-averaged spectrum from T0-5 s to T0+4 s is best fit by a Band function with Epeak = 25 +/- 2 keV, alpha = -0.4 +/- 0.5, and beta = -2.5 +/- 0.1 The event fluence (8-1000 keV) in this time interval is (1.8 +/- 1.3)E-6 erg/cm^2, with a 1 sec peak flux starting at T0 of 9.6 +/- 4.2 ph/cm^2/s and a 0.256 sec peak flux starting at T0+0.256 sec of 18.6 +/- 8.0 ph/cm^2/s. In view of the soft spectrum and the position of the burster close to the Galactic plane, other spectral forms were investigated that are more typical of galactic transient sources. Of these, the best fit was obtained using a thermal Bremmstrahlung model with kT = 49. The Band GRB function was preferred statistically with delta chi2 = -5 for 1 extra parameter. It is likely, therefore, that this is a soft GRB rather than a new galactic transient. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."