TITLE: GCN CIRCULAR NUMBER: 20660 SUBJECT: GRB 170210A: Fermi GBM observation DATE: 17/02/10 17:54:44 GMT FROM: Bagrat Mailyan at UAH O.J. Roberts (USRA/NASA) and B. Mailyan (UAH) report on behalf of the Fermi GBM Team: "At 02:47:36.58 UT on February 10th 2017, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 170210A (trigger 508387661 / 170210116). The on-ground calculated location using the GBM trigger data is, RA = 232.56, DEC = -58.59 (J2000 degrees), equivalent to J2000 15h 30m, -58d 35', 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 109 degrees. The GBM light curve shows a long burst with multiple episodes of bright emission over a duration (T90) of about 79 s (50-300 keV). The time-averaged spectrum from T0+9 s to T0+84 s is best fit by a Band function with alpha= -0.90 +/- 0.02, beta= -2.28 +/- 0.08 and Epeak is 361.5 +/- 14.1 keV. The event fluence (10-1000 keV) in this time interval is (1.10 +/- 0.2) E-04 erg/cm^2. The 1s peak photon flux measured starting from T0+41.7 s in the 10-1000 keV band is 32.8 +/- 0.6 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."