TITLE:   GCN CIRCULAR
NUMBER:  32829
SUBJECT: GRB 221021A: Fermi GBM observation
DATE:    22/10/24 17:09:01 GMT
FROM:    Elisabetta Bissaldi at INFN,Bari  <elisabetta.bissaldi@ba.infn.it>

E. Bissaldi (Politecnico and INFN Bari) and
C. Meegan (UAH) report on behalf of the Fermi GBM Team:


"At 09:18:25.74 UT on 21 October 2022,
the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 221021A
(trigger 688036710 / 221021388),
which was also detected by the Swift/BAT-GUANO
(Raman et al. 2022, GCN 32817).

The GBM position is reported in the Fermi-GBM
Final Real-time Localization (GCN 32812).
The angle from the Fermi LAT boresight
at the GBM trigger time is 132 degrees.

The GBM light curve shows a multipeaked emission
with a duration (T90) of about 68 s (50-300 keV).
The time-averaged spectrum from T0 to T0+60 s is
best fit by a power law function with an exponential
high-energy cutoff.
The power law index is -1.16 +/- 0.03 and the cutoff
energy, parameterized as Epeak, is 2000 +/- 210 keV.

The event fluence (10-1000 keV) in this time interval is
(3.06 +/- 0.07)E-05 erg/cm^2.
The 1-sec peak photon flux measured
starting from T0+34 s in the 10-1000 keV band
is 9.1 +/- 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/"