TITLE: GCN CIRCULAR NUMBER: 23044 SUBJECT: GRB 180727A: Fermi GBM observation DATE: 18/07/27 19:30:47 GMT FROM: Peter Veres at UAH P. Veres (UAH) reports on behalf of the Fermi GBM Team: "At 14:15:28.81 UT on 27 July 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 180727A (trigger 554393733 / 180727594) which was also detected by Swift (Beardmore et al., GCN 23043). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 46 degrees. The GBM light curve consists of a single pulse with a duration (T90) of about 1.1 s (50-300 keV). The time-averaged spectrum from T0-0.19 s to T0+0.83 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is 0.14 +/- 0.28 and the cutoff energy, parameterized as Epeak, is 69 +/- 4 keV. The event fluence (10-1000 keV) in this time interval is (3.32 +/- 0.18)E-7 erg/cm^2. The 64-msec peak photon flux measured starting from T0+0.45 s in the 10-1000 keV band is 7.2 +/- 1.2 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."