TITLE: GCN CIRCULAR NUMBER: 28843 SUBJECT: GRB 201105B: Fermi GBM observation DATE: 20/11/05 23:54:22 GMT FROM: Christian Malacaria at NASA-MSFC/USRA E. Bissaldi (Politecnico and INFN Bari) and S. Lesage (UAH) report on behalf of the Fermi GBM Team: "At 05:09:32.233 UT on 5 November 2020, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 201105B (trigger 626245777 / 201105215). The on-ground calculated location, using the GBM trigger data, is RA = 244.5, DEC = 16.0 (J2000 degrees, equivalent to 16h 18m, -16d 02'), with an uncertainty of 1.0 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a mixture of two Gaussians, one with a radius of 1.8 degrees (52% contribution) and one with a radius of 4.1 degrees (47% contribution) [A. Goldstein et al. 2020, ApJ, 895, 1] ). The angle from the Fermi LAT boresight at the GBM trigger time is 92 degrees. The GBM light curve shows a FRED emission episode with a duration (T90) of about 17 s (50-300 keV). The time-averaged spectrum from T0 to T0+23 s is best fit by a Band function with Epeak = 512 +/- 21 keV, alpha = -0.95 +/- 0.01, and beta = -2.35 +/- 0.09. The event fluence (10-1000 keV) in this time interval is (5.13 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+2.7 s in the 10-1000 keV band is 28.5 +/- 0.5 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/"