GCN Circular 11015
Subject
GRB 100728B: Fermi GBM observation
Date
2010-07-28T13:47:40Z (14 years ago)
From
Andreas von Kienlin at MPE <azk@mpe.mpg.de>
A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team:
"At 10:31:54.97 UT on 28 July 2010, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 100728B (trigger 302005916 / 100728439),
which was also detected by the Swift-BAT (Morris et al. 2008, GCN 11009)
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is 57.1 degrees.
The GBM light curve shows a single pulse
with a duration (T90) of about 11.8 +/- 2.4 s (50-300 keV).
The time-averaged spectrum from T0-1.024 s to T0+5.632 s is
well fit by a power law function with an exponential
high energy cutoff. The power law index is -0.9 +/- 0.1 and
the cutoff energy, parameterized as Epeak, is 131 +/- 15 keV
(chi squared 1043 for 599 d.o.f.).
The event fluence (8-1000 keV) in this time interval is
(2.4 +/- 0.1)E-06 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+1.22 s in the 8-1000 keV band
is 6.2 +/- 0.2 ph/s/cm^2.
A Band function fits the spectrum equally well (chi squared 1037
for 598 d.o.f.) with Epeak= 104 +/- 14 keV, alpha = -0.8 +/- 0.2
and beta = -2.2 +/-0.2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."