TITLE: GCN CIRCULAR NUMBER: 15175 SUBJECT: GRB 130903A: Fermi GBM observation DATE: 13/09/04 04:12:11 GMT FROM: Shaolin Xiong at UAH Shaolin Xiong (UAH) and Charles Meegan (UAH) report on behalf of the Fermi GBM Team: "At 00:47:32.37 UT on 03 September 2013, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 130903A (trigger 399862055 / 130903033), which was also detected by the INTEGRAL (Mereghetti et al., GCN 15169) and Swift/XRT (Grupe et al., GCN 15173). The GBM on-ground location is consistent with the INTEGRAL and Swift position. The angle from the Fermi LAT boresight is 33 degrees. The GBM light curve consists of multiple pulses with a duration (T90) of about 69 +/- 7 s (50-300 keV). The time-averaged spectrum from T0-2 s to T0+68 s is well fit by a power law function with an exponential high-energy cutoff. The power law index is -0.70 +/- 0.27 and the cutoff energy, parameterized as Epeak, is 41 +/- 3 keV. The event fluence (10-1000 keV) in this time interval is (2.0 +/- 0.1)E-6 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.22 s in the 10-1000 keV band is 1.3 +/- 0.2 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."