TITLE: GCN CIRCULAR NUMBER: 21218 SUBJECT: GRB 170607A: Fermi GBM observation DATE: 17/06/08 09:02:25 GMT FROM: Elisabetta Bissaldi at U.Innsbruk/IAPP R. Hamburg (UAH) and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 23:17:59.57 UT on 07 June 2017, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 170607A (trigger 518570284 / 170607971), which was also detected by the Swift/BAT (D'Ai et al. 2017, GCN 21214). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 100 degrees. The GBM light curve consists of a sharp peak with a duration (T90) of about 23 s (50-300 keV). The time-averaged spectrum from T0-2.4 s to T0+14.0 s is adequately fit by a power law function with an exponential high-energy cutoff. The power law index is -1.40 +/- 0.04 and the cutoff energy, parameterized as Epeak, is 154 +/- 13 keV. The event fluence (10-1000 keV) in this time interval is (9.6 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+2.1 s in the 10-1000 keV band is 15.5 +/- 0.6 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."