TITLE: GCN CIRCULAR NUMBER: 19724 SUBJECT: GRB 160720A: Fermi GBM detection DATE: 16/07/21 01:53:43 GMT FROM: Rachel Hamburg at UAH R. Hamburg (UAH) and E. Burns (UAH) report on behalf of the Fermi GBM Team: "At 18:23:57.00 UT on 20 July 2016, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 160720A (trigger 490731840 / 160720767). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 43, Dec = +76, with a statistical uncertainty of 1.00 degrees; 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 is 131 degrees. The GBM light curve consists of several overlapping peaks with a duration (T90) of about 79 s (50-300 keV). The time-averaged spectrum from T0-1.02 to T0+154 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.12 +/- 0.01 and the cutoff energy, parameterized as Epeak, is 191 +/- 3 keV. The event fluence (10-1000 keV) in this time interval is (151 +/- 1)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+88 s in the 10-1000 keV band is 58 +/- 1 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."