TITLE: GCN CIRCULAR NUMBER: 20350 SUBJECT: GRB 170101B: Fermi GBM detection DATE: 17/01/01 10:24:47 GMT FROM: Andreas von Kienlin at MPE P Veres (UAH) and C Meegan (UAH) report on behalf of the Fermi GBM Team: "At 02:47:17.87 UT on 01 January 2017, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 170101B (trigger 504931642 / 170101116). The on-ground calculated location, using the GBM trigger data, is RA = 70.6, DEC = -1.6 (J2000 degrees, equivalent to 04 h 43 m, -1 d 35 '), with an uncertainty of 1.2 degrees (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 angle from the Fermi LAT boresight at the GBM trigger time is 65 degrees. The GBM light curve shows/consists of two overlapping pulses with a duration (T90) of about 12.8 s (50-300 keV). The time-averaged spectrum from T0 to T0 + 15.7 s is best fit by a Band function with Epeak = 213 +/- 13 keV, alpha = -0.57 +/- 0.05, and beta = -2.29 +/- 0.12. The event fluence (10-1000 keV) in this time interval is (1.26 +/- 0.03)E-5 erg/cm^2. The 1-sec peak photon flux measured starting from T0 + 6.1 s in the 10-1000 keV band is 7.0 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."