TITLE:   GCN CIRCULAR
NUMBER:  33203
SUBJECT: GRB 230116B: Fermi GBM observation
DATE:    23/01/21 17:53:00 GMT
FROM:    Rachel Hamburg at UAH  <rkh0007@uah.edu>

R. Hamburg (CNRS/IJCLab) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 08:59:06.67 UT on 16 January 2023, the Fermi Gamma-Ray Burst Monitor
(GBM)
triggered and located GRB 230116B (trigger 695552351 / 230116374), which
was
also localized by the IPN network (Kozyrev et al. 2023, GCN 33200).
The GBM on-ground location is consistent with the IPN position.

The angle from the Fermi LAT boresight at the GBM trigger time is 104
degrees.

The GBM light curve consists of a single pulse with a duration (T90) of
about 64 ms (50-300 keV). The time-averaged spectrum from T0-0.064 s to
T0+0.128 is best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.07 +/- 0.09 and
the cutoff energy, parameterized as Epeak, is 733 +/- 53 keV.

The event fluence (10-1000 keV) in this time interval is
(3.7 +/- 0.1)E-06 erg/cm^2. The 64-ms peak photon flux measured
starting from T0+0.0 s in the 10-1000 keV band is 75.5 +/- 3.0 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/"