GCN Circular 20551
P. Veres and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 15:13:28.77 UT on 27 January 2017, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 170127B (trigger 507222813 / 170127634) which was also detected by the Swift/BAT (Cannizzo et al., GCN 20540). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 44 degrees. The GBM light curve shows two overlapping pulses with a duration (T90) of about 1.7 s (50-300 keV). The time-averaged spectrum from T0-0.1 s to T0+0.4 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.67 +/- 0.16 and the cutoff energy, parameterized as Epeak, is 688 +/- 195 keV. The event fluence (10-1000 keV) in this time interval is (7.6 +/- 0.6)E-7 erg/cm^2. The 64 ms peak photon flux measured starting from T0-64 ms in the 10-1000 keV band is 8.4 +/- 1.2 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."