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/"