TITLE: GCN CIRCULAR NUMBER: 23053 SUBJECT: GRB 180728A: Fermi GBM observation DATE: 18/07/29 04:18:59 GMT FROM: Peter Veres at UAH P. Veres, C. Meegan, and B. Mailyan (all UAH) report on behalf of the Fermi GBM Team: "At 17:29:02.28 UT on 28 July 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 180728A (trigger 554491747 / 180728728) which was also detected by the Swift/BAT (Starling et al., GCN 23046). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 35 degrees. The GBM light curve consists of a precursor and a very bright peak with a duration (T90) of about 6.4 s (50-300 keV). The time-averaged spectrum from T0+9.2s to T0+23.6 s is best fit by a Band function with Epeak = 79.2 +/- 1.4 keV, alpha = -1.54 +/- 0.01, and beta = -2.46 +/- 0.02. The event fluence (10-1000 keV) in this time interval is (5.65 +/- 0.02)E-5 erg/cm^2. The 1-sec peak photon flux measured starting from T0+11.1 s in the 10-1000 keV band is 231.0 +/- 1.2 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." [GCN OPS NOTE(29jul18): As pointed out by A.Kann, the "170728A" in the Subject-line was corrected to "180728A".]