GCN Circular 33353
Subject
GRB 230217A: Fermi GBM observation
Date
2023-02-20T14:57:16Z (a year ago)
From
Peter Veres at UAH <veresp@gmail.com>
P. Veres (UAH) reports on behalf of the Fermi GBM Team:
"At 21:53:10.69 UT on 17 February 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 230217A (trigger 698363595 / 230217912).
which was also detected by the Swift/BAT (Moss et al., GCN 33339),
AGILE (Casentini et al., GCN 33343), CALET-GBM (Torii et al., GCN
33342) and Konus-Wind (Svinkin et al., GCN 33349). The GBM on-ground
location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 58 degrees.
The GBM light curve consists of a single pulse
with a duration (T90) of about 0.90 s (50-300 keV).
The time-averaged spectrum from T0s to T0+1.4 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.74 +/- 0.02 and
the cutoff energy, parameterized as Epeak, is 1497 +/- 63 keV.
The event fluence (10-1000 keV) in this time interval is
(1.81 +/- 0.02)E-5 erg/cm^2. The 64 ms peak photon flux measured
starting from T0+0.22 s in the 10-1000 keV band
is 93.1 +/- 2.8 ph/s/cm^2.
A Band function fits the spectrum equally well
with Epeak= 1476 +/- 79 keV, alpha = -0.74 +/- 0.02 and beta = 3.07+/-0.82.
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/"