TITLE: GCN CIRCULAR NUMBER: 22634 SUBJECT: GRB 180411A: Fermi GBM detection DATE: 18/04/12 02:41:57 GMT FROM: Suraj Poolakkil at UAH S. Poolakkil (UAH), A. von Kienlin (MPE) and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 12:27:40.97 UT on 11 April 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 180411A (trigger 545142465 / 180411519), which was also detected by the Swift/BAT (Liu et al. 2018, GCN 22630). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 150 degrees. The GBM light curve shows two peaks with a duration (T90) of about 77.6 s (50-300 keV). The time-averaged spectrum from T0-3.1 s to T0+79.8 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.18 +/- 0.05 and the cutoff energy, parameterized as Epeak, is 358 +/- 30 keV. The event fluence (10-1000 keV) in this time interval is (3.276 +/- 0.085)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+54.27 s in the 10-1000 keV band is 10.5 +/- 0.79 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."