TITLE: GCN CIRCULAR NUMBER: 17319 SUBJECT: GRB 150120A: Fermi GBM observation DATE: 15/01/20 13:49:42 GMT FROM: Andreas von Kienlin at MPE A. von Kienlin (MPE) and E. Burns (UAH) report on behalf of the Fermi GBM Team: "At 02:57:47.00 UT on 20 January 2015, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 150120A (trigger 443415470/150120123), which was also detected by the Swift/BAT & XRT (D'Elia et al. 2015, GCN 17310). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 98 degrees. The GBM light curve shows a single pulse with a duration (T90) of about 2 s (50-300 keV). The time-averaged spectrum from T0-1.024 s to T0+0.512 s is well fit by a power law function with an exponential high-energy cutoff. The power law index is -1.43 (+0.28/-0.24) and the cutoff energy, parameterized as Epeak, is 130 (+150/-50) keV The event fluence (10-1000 keV) in this time interval is (3.4 +/- 0.8)E-07 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0-0.64 s in the 10-1000 keV band is 3.1 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."