TITLE:   GCN CIRCULAR
NUMBER:  31508
SUBJECT: GRB 220117C: Fermi GBM Observation
DATE:    22/01/20 20:58:15 GMT
FROM:    Stephen Lesage at Fermi-GBM Team  <sjl0014@uah.edu>

S. Lesage (UAH) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 04:45:55 UT on 17 January 2022, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 220117C (trigger 664087560/220117199)
which was also detected by Swift/BAT-GUANO (Raman et al. 2022, GCN 31501).
The Fermi GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight is 73 degrees.

The GBM light curve consists of multiple pulses with a duration (T90)
of about 115 s (10-1000 keV). The time-averaged spectrum
from T0-1.8 to T0+114.9 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is 0.1 +/- 0.3 and the cutoff energy,
parameterized as Epeak, is 82 +/- 6 keV.

The event fluence (10-1000 keV) in this time interval is
(4.6 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+4.7 s in the 10-1000 keV band is 6.4 +/- 0.3 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/"