TITLE: GCN CIRCULAR NUMBER: 17525 SUBJECT: GRB 150301B: Fermi GBM detection DATE: 15/03/02 05:26:50 GMT FROM: Eric Burns at U of Alabama E. Burns (UAH) and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 19:38:04.51 UT on 01 March 2015, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 150301B (trigger 446931487/150301818) which was also detected by the Swift/BAT (Lien et al. 2015, GCN 17515). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 39 degrees. The GBM light curve consists of one main peak with a duration (T90) of about 13 s (50-300 keV). The time-averaged spectrum from T0-2.560 s to T0+13.824 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.2 +/- 0.1 and the cutoff energy, parameterized as Epeak, is 256 +/- 32 keV. A Band function fits the spectrum equally well with Epeak= 180 +/- 38 keV, alpha = -1.1 +/- 0.1 and beta = -2.0 +/- 0.2. The event fluence (10-1000 keV) in this time interval is (4.4 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+2.560 s in the 10-1000 keV band is 4.5 +/- 0.2 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."