TITLE: GCN CIRCULAR NUMBER: 30965 SUBJECT: GRB 211023A: Fermi GBM detection DATE: 21/10/24 05:04:53 GMT FROM: Suraj Poolakkil at UAH <sp0076@uah.edu> S. Lesage (UAH), S. Poolakkil (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 13:05:43 UT on 23 October 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 211023A (trigger 656687148/211023546) which was also detected by Fermi-LAT (N. Di Lalla et al. 2021, GCN 30961). The Fermi GBM Final Real-time Localization (GCN 30958) is consistent with the Fermi-LAT position. The angle from the Fermi LAT boresight is 53 degrees. The GBM light curve consists of two emission episodes with a duration (T90) of about 80 s (10-1000 keV). The time-averaged spectrum from T0+53 to T0+158 s is best fit by a Band function with Epeak = 92 +/- 2 keV, alpha = -1.74 +/- 0.01, and beta = -2.55 +/- 0.07. The event fluence (10-1000 keV) in this time interval is (1.114 +/- 0.007)E-08 erg/cm^2. The 1-sec peak photon flux measured starting from T0+72.1 s in the 10-1000 keV band is 27.4 +/- 0.7 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/"