TITLE: GCN CIRCULAR NUMBER: 34750 SUBJECT: GRB 230919A: Fermi GBM Observation DATE: 23/09/20 20:49:41 GMT FROM: Lorenzo Scotton at UAH <lscottongcn@outlook.com> L. Scotton (UAH), C. Fletcher (USRA) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 16:58:23.86 UT on 19 September 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230919A (trigger 716835508/230919707). which was also detected by AstroSat (Navaneeth et al. 2023, GCN 34742) and Swift/BAT-GUANO (DeLaunay et al. 2023, GCN 34747). The Fermi GBM Final Real-time Localization was reported in GCN 34737. The angle from the Fermi LAT boresight is 120 degrees. The GBM light curve consists of multiple peaks with a duration (T90) of about 2.9s. The time-averaged spectrum from T0-0.06 to T0+1.34 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.74 +/- 0.06 and the cutoff energy, parameterized as Epeak, is 2023 +/- 271 keV. A Band function fits the spectrum equally well with Epeak = 1617 +/- 352 keV, alpha = -0.68 +/- 0.08 and beta = -2.43 +/- 0.32. The event fluence (10-1000 keV) in this time interval is (3.3 +/- 0.1)E-06 erg/cm^2. The 64-msec peak photon flux measured starting from T0+0.58 s in the 10-1000 keV band is 12 +/- 2 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/" View this GCN Circular online at https://gcn.nasa.gov/circulars/34750. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...