TITLE: GCN CIRCULAR NUMBER: 22164 SUBJECT: GRB 171124A: Fermi GBM observation DATE: 17/11/24 16:35:48 GMT FROM: Elisabetta Bissaldi at U.Innsbruk/IAPP E. Bissaldi (Politecnico & INFN Bari) and A. von Kienlin (MPE) report on behalf of the Fermi GBM Team: "At 05:37:56.50 UT on 24 November 2017, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 171124A (trigger 533194681 / 171124235), which was also detected by Fermi LAT (Longo et al. 2017, GCN 22156). The GBM on-ground location is consistent with the LAT position. The angle from the Fermi LAT boresight at the GBM trigger time is 19 degrees. The GBM light curve consists of two emission episodes with a duration (T90) of about 26 s (50-300 keV). The time-averaged spectrum from T0-1.3 s to T0+22 s is well fit by a Band function with Epeak = 1.12 +/- 0.28 MeV, alpha = -1.01 +/- 0.05, and beta = -2.10 +/- 0.22. The event fluence (10-1000 keV) in this time interval is (1.1 +/- 0.3)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+7.3 s in the 10-1000 keV band is 4.5 +/- 0.2 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."