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GCN Circular 33083

Subject
GRB 221215A: Fermi GBM Detection
Date
2022-12-19T15:24:17Z (a year ago)
From
Oliver J Roberts at USRA/NASA <oliver.roberts@nasa.gov>
O.J. Roberts (USRA/NASA), J. Wood (NASA) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 04:14:27.97 UT on 15 December 2022, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 221215A (trigger 692770472 / 221215177)
which was also detected by the Swift/BAT GUANO (DeLaunay et al. 2022, GCN 33062)
The Fermi GBM Final Real-time Localization (GCN 33054) is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 53 degrees.

The GBM light curve shows a FRED-like pulse
with a duration (T90) of about 14 s (50-300 keV).
The time-averaged spectrum from T0-2 s to T0+12 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is 1.6 +/- 1.3 and
the cutoff energy, parameterized as Epeak, is 165 +/- 26 keV

The event fluence (10-1000 keV) in this time interval is
(6.8 +/- 1.2)E-07 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.7 s in the 10-1000 keV band
is 29.8 +/- 9.4 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/"
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