GCN Circular 20835
Subject
GRB 170307A: Fermi GBM observation
Date
2017-03-08T05:44:32Z (7 years ago)
From
C. Michelle Hui at MSFC/Fermi-GBM <c.m.hui@nasa.gov>
C.M. Hui (NASA/MSFC) and O.J. Roberts (USRA/NASA)
report on behalf of the Fermi GBM Team:
At 20:25:17.49 UT on 07 March 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170307A (trigger 510611122 /170307851),
which was also detected by Swift BAT (A. Y. Lien et al., GCN 20832).
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time
using the Swift-BAT location is 98 degrees.
The GBM light curve consists of multiple peaks with a duration (T90)
of about 57.9s (50-300 keV). The time-averaged spectrum
from T0-27.6s to T0+28.7 s is adequately fit by a power law function
with an exponential high-energy cutoff. The power law index
is -1.18 +/- 0.26 and the cutoff energy, parameterized as Epeak,
is 83.80 +/- 19.90 keV.
The event fluence (10-1000 keV) in this time interval is
(1.85 +/- 0.25)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+8.3 s in the 10-1000 keV band is
1.72 +/- 0.25 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog.