TITLE: GCN CIRCULAR NUMBER: 25277 SUBJECT: GRB 190805B: Fermi GBM detection DATE: 19/08/05 21:16:24 GMT FROM: Rachel Hamburg at UAH R. Hamburg (UAH) and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 04:46:00.97 UT on 05 August 2019, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 190805B (trigger 586673165 / 190805199), which was also detected by the MAXI/GSC (Sato et al. 2019, GCN 25271). The Fermi GBM Final Real-time Localization (GCN 25270) is consistent with the MAXI position. The angle from the Fermi LAT boresight at the GBM trigger time is 46 degrees. The GBM light curve shows a spiky, multi-peaked structure with a duration (T90) of about 22 s (50-300 keV). The time-averaged spectrum from T0-4.6 s to T0+ 25.1 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.07 +/- 0.05 and the cutoff energy, parameterized as Epeak, is 389 +/- 51 keV. The event fluence (10-1000 keV) in this time interval is (1.03 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+16 s in the 10-1000 keV band is 7.6 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"