GCN Circular 17417
E. Burns (UAH) and H.-F Yu (MPE) report on behalf of the Fermi GBM Team: "At 09:46:27.48 UT on 06 February 2015, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 150206B (trigger 444908790 / 150206407). The on-ground calculated location, using the GBM trigger data, is RA = 220.6, DEC = +57.5 (J2000 degrees, equivalent to 14 h 42 m, 57 d 30 '), with an uncertainty of 6.8 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). The angle from the Fermi LAT boresight is 76 degrees. Early follow-up observations of the GBM location error box by the intermediate Palomar Transient Factory yielded three possible optical counterparts (Singer et al. 2015, GCN 17415). The GBM light curve consists of a single main peak with a duration (T90) of about 5 s (50-300 keV). The time-averaged spectrum from T0-1.024 s to T0+4.096 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.50 +/- 0.15 and the cutoff energy, parameterized as Epeak, is 72 +/- 4 keV. The event fluence (10-1000 keV) in this time interval is (1.1 +/- 0.05)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.576 s in the 10-1000 keV band is 5.2 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."