TITLE: GCN CIRCULAR NUMBER: 19973 SUBJECT: GRB 161001A: Fermi GBM detection DATE: 16/10/01 15:25:32 GMT FROM: Peter Veres at UAH P Veres, M Stanbro and C Meegan (UAH) report on behalf of the Fermi GBM Team: "At 01:05:16.72 UT on 01 October 2016, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 161001A (trigger 496976720 / 161001045) which was also detected by the Swift/BAT (Page et al., GCN 19967). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 37 degrees. The GBM light curve consists of a dominant pulse preceded by weaker emission with a duration (T90) of about 2.2 s (50-300 keV). The time-averaged spectrum from T0-1.1 s to T0+2.9 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.89 +/- 0.10 and the cutoff energy, parameterized as Epeak, is 313 +/- 54 keV. The event fluence (10-1000 keV) in this time interval is (2.3 +/- 0.2)E-6 erg/cm^2. The 1-sec peak photon flux measured starting from T0+1.2 s in the 10-1000 keV band is 6.9 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."