TITLE: GCN CIRCULAR NUMBER: 20219 SUBJECT: GRB 161129A: Fermi GBM Detection DATE: 16/11/30 01:21:31 GMT FROM: Rachel Hamburg at UAH O.J. Roberts (UCD), C. Meegan (UAH), and R. Hamburg (UAH) report on behalf of the Fermi GBM Team: "At 07:11:39.96 UT on the 29th of November 2016, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 161129A (trigger 502096303/161129300), which was also detected by Swift (Kocevski et al., GCN 20210). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 87 degrees using the Swift position. The GBM light curve shows a bright burst, with multiple peaks over a duration (T90) of about 36 s (50-300 keV). The time-averaged spectrum from T0+4.8 s to T0+45.7 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.13 +/- 0.06 and the cutoff energy, parameterized as Epeak, is 197 +/- 21 keV. The event fluence (10-1000 keV) in this time interval is (8.4 +/- 0.4)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+26 s in the 10-1000 keV band is 5.6 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."