TITLE:   GCN CIRCULAR
NUMBER:  34831
SUBJECT: GRB 231018A: Fermi GBM Detection
DATE:    23/10/18 17:36:50 GMT
FROM:    Stephen Lesage at Fermi-GBM Team <sjl0014@uah.edu>

S. Lesage (UAH), E. Bissaldi (Politecnico and INFN Bari) and C. Meegan (UAH)
report on behalf of the Fermi Gamma-ray Burst Monitor Team:

"At 12:30:10 UT on 18 October 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 231018A (trigger 719325015/231018521).
The Fermi GBM Final Real-time Localization is reported in GCN 34826.

The angle from the Fermi LAT boresight is 131 degrees.

The GBM light curve consists of multiple multiple pulses with a duration (T90)
of about 39.4 s (50-300 keV). The time-averaged spectrum
from T0-4.6 to T0+92.7 s is best fit by
a Band function with Epeak = 109 +/- 3 keV,
alpha = -1.24 +/- 0.02, and beta = -2.56 +/- 0.05.

The event fluence (10-1000 keV) in this time interval is
(1.192 +/- 0.009)E-04 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+57 s in the 10-1000 keV band is 75 +/- 1 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/"