GCN Circular 25248
O.J. Roberts (USRA) and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 22:38:20.37 UT on 31 July 2019, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 190731A (trigger 586305505 / 190731943), which was also detected by the LAT (Ohno et al., GCN 25244). The GBM on-ground location is consistent with the LAT position. The initial angle from the Fermi LAT boresight to the best location is 40 degrees. The GBM light curve consists of several bright peaks with a duration (T90) of 15.9 +/- 0.4 s (50-300 keV). The time-averaged spectrum from T0+1.6 s to T0+17.9 s is best fit by a Band function with Epeak = 456 +/- 9, alpha index = -0.74 +/- 0.01 and beta index = -2.40 +/- 0.05. The event fluence (10-1000 keV) in this time interval is (8.57 +/- 0.05)E-05 erg/cm^2. The 1s peak photon flux measured starting from T0+1.9 s in the 10-1000 keV band is 55.5 +/- 0.4 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/"