GCN Circular 8793
Subject
GRB090107B: Fermi GBM Detection
Date
2009-01-09T23:33:40Z (15 years ago)
From
Adam Goldstein at Fermi-GBM/UAH <adam.m.goldstein@msfc.nasa.gov>
A. Goldstein (UAH), R. Preece (UAH), and A.J. van der Horst (NASA/ORAU)
report on behalf of the Fermi GBM Team:
"At 16:20:42.77 UT on 07 January 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090107B (trigger 25303844 / 090107681).
This burst was also detected by the INTEGRAL IBAS
(D. Gotz et al. 2009, GCN 8786)
The GBM on-ground location is consistent with the INTEGRAL position.
The GBM light curve consists of two main emission peaks and apparent
substructure with a duration (T90) of about 24.1 s (8-1000 keV).
The time-averaged spectrum from T0-4.1 s to T0+20.5 s is
best fit by a power law function with an exponential
high energy cutoff. The power law index is -0.68 +/- 0.26 and
the cutoff energy, parameterized as Epeak, is 106.1 +/- 14.8 keV
(chi squared 530.4 for 486 d.o.f.).
The event fluence (8-1000 keV) in this time interval is
(1.75 +/- 0.37)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+6.1 s in the 8-1000 keV band
is 3.68 +/- 0.27 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."