GCN Circular 23057
R. Hamburg, P. Veres, and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 21:09:58.91 UT on 28 July 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 180728B (trigger 554505003 / 180728882). which was also localized by IPN (GCN 23056). The angle from the Fermi LAT boresight at the GBM trigger time is 96 degrees. The GBM light curve shows a structured spike with a duration (T90) of about 0.6 s (50-300 keV). The time-averaged spectrum from T0-0.06 s to T0+0.38 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.18 +/- 0.15 and the cutoff energy, parameterized as Epeak, is 504 +/- 61 keV. The event fluence (10-1000 keV) in this time interval is (1.36 +/- 0.90)E-06 erg/cm^2. The 64-ms peak photon flux measured starting from T0+0.19 s in the 10-1000 keV band is 16.5 +/- 1.7 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."