TITLE: GCN CIRCULAR NUMBER: 23953 SUBJECT: GRB 190311A: Fermi GBM observation DATE: 19/03/12 02:09:13 GMT FROM: Peter Veres at UAH P. Veres and C. Meegan (both UAH) report on behalf of the Fermi GBM Team: "At 14:23:37.601 UT on 11 March 2019, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 190311A (trigger 574007022 / 190311600), which was also detected by the Swift/BAT (Troja et al., GCN 23946). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 128 degrees. The GBM light curve consists of a single peak with a duration (T90) of about 12.5 s (50-300 keV). The time-averaged spectrum from T0-4.1 s to T0+3.1 s is adequately fit by a simple power law function with index 1.86 +/- 0.08. The event fluence (10-1000 keV) in this time interval is (1.40 +/- 0.18)E-6 erg/cm^2. The 1-sec peak photon flux measured starting from T0-2.75 s in the 10-1000 keV band is 3.00 +/- 0.35 ph/s/cm^2. A power law function with an exponential high-energy cutoff fits the spectrum equally well with Epeak= 89 +/- 34 keV and alpha = -1.51 +/- 0.25. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."