TITLE: GCN CIRCULAR NUMBER: 24794 SUBJECT: GRB 190611B: Fermi GBM detection DATE: 19/06/12 18:39:54 GMT FROM: Christian Malacaria at NASA-MSFC/USRA C. Malacaria (NASA-MSFC/USRA) and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 22:47:49.34 UT on the 11th of June 2019, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 190611B (trigger 581986074 / 190611950). The on-ground calculated location, using the GBM trigger data, is RA = 88.9, DEC = 53.1 (J2000 degrees, equivalent to 05 h 56 m, 53 d 07 '), with a statistical uncertainty of 1.0 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a core-plus-tail model, with 90% of GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg systematic error [Connaughton et al. 2015, ApJS, 216, 32] ). The angle from the Fermi LAT boresight at the GBM trigger time is 117.0 degrees. The GBM light curve consists of two broad pulses with a duration (T90) of about 100.6 s (50-300 keV). The time-averaged spectrum from T0-0.0 s to T0+18.2 s is best fit by a Band function with Epeak = 210.3 +/- 18.9 keV, alpha = -1.00 +/- 0.04, and beta = -1.98 +/- 0.05 The event fluence (10-1000 keV) in this time interval is (2.43 +/- 0.40)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+71.8 s in the 10-1000 keV band is 32.4 +/- 0.6 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/" [GCN OPS NOTE(16jun19), Per author's request, the "190611A" in the first sentence was corrected to "190611B".]