TITLE: GCN CIRCULAR NUMBER: 20630 SUBJECT: GRB 170207A: Fermi GBM observation DATE: 17/02/08 18:17:45 GMT FROM: Oliver J Roberts at USRA/NASA O.J. Roberts (USRA/NASA), B. Mailyan (UAH) and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 21:45:03.67 UT on February 7th 2017, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 170207A (trigger 508196708 /170207906). This event was also detected by Konus Wind (Svinkin et al, GCN 20629) and localized by the IPN (Svinkin et al, GCN 20628). The on-ground calculated location using the GBM trigger data is, RA = 325.87, DEC = +50.05 (J2000 degrees), equivalent to J2000 21h 43m, +50d 03', with an uncertainty of 1 degree (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a core-plus-tail model, with 90% of GRBs having a 3.7 deg. error and a small tail suffering a larger than 10 deg. systematic error [Connaughton et al. 2015, ApJS, 216, 32]). The initial angle from the Fermi-LAT boresight to the GBM ground-location is 94 degrees. The GBM light curve shows a long burst with multiple episodes of bright emission over a duration (T90) of about 39 s (50-300 keV). The time-averaged spectrum from T0+0 s to T0+39 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.92 +/- 0.02 and the cutoff energy, parameterized as Epeak, is 499.4 +/- 19.5 keV. A Band function fits the spectrum equally well, with alpha= -0.91 +/- 0.02, beta= -2.68 +/- 0.28 and Epeak is 478.8 +/- 23.1 keV. The event fluence (10-1000 keV) in this time interval is (5.86 +/- 0.07) E-05 erg/cm^2. The 1s peak photon flux measured starting from T0+20.5 s in the 10-1000 keV band is 25.4 +/- 0.4 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."