TITLE:   GCN CIRCULAR
NUMBER:  32830
SUBJECT: GRB 221022B: Fermi GBM detection
DATE:    22/10/24 17:28:04 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076@uah.edu>

S. Poolakkil (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 22:55:48.91 UT on 22 October 2022, the Fermi Gamma-Ray Burst Monitor
(GBM)
triggered and located GRB 221022B (trigger 688172153 / 221022955, GCN 32820)
which was also detected by the Swift/BAT- GUANO (Raman et al. 2022, GCN
32823).

The angle from the Fermi LAT boresight at the GBM trigger time is 93
degrees.

The GBM light curve consists of a single peak followed
by some extended emission with a duration (T90) of about 32 s (50-300 keV).
The time-averaged spectrum from T0+7.17 s to T+46.08 s
is best fit by Band function, with Epeak = 265 +/- 6 keV,
alpha = -0.61 +/- 0.02 and beta = -2.61 +/- 0.10.

The event fluence (10-1000 keV) in this time interval is
(7.14 +/- 0.07)E-05  erg/cm^2. The 1-sec peak photon flux measured
starting from T0+22.3 s in the 10-1000 keV band
is 34.3 +/- 0.5 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/"