GCN Circular 23135
Subject
GRB 180812A: Fermi GBM detection
Date
2018-08-12T20:52:06Z (6 years ago)
From
Rachel Hamburg at UAH <rkh0007@uah.edu>
A. von Kienlin (MPE), R. Hamburg (UAH), and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:
"At 08:22:30.31 UT on 12 August 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180812A (trigger 555754955 / 180812349),
which was also detected by the Swift BAT and XRT instruments (Lien et al.
2008, GCN 23129). The GBM on-ground location is consistent with the Swift
position.
The angle from the Fermi LAT boresight at the GBM trigger time is 46
degrees.
The GBM light curve shows several peaks with a duration (T90) of about 38 s
(50-300 keV). The time-averaged spectrum from T0-2.0 s to T0+34.8 s is
adequately fit by a power law function with an exponential high-energy
cutoff.
The power law index is -0.56 +/- 0.36 and the cutoff energy, parameterized
as Epeak, is 110 +/- 25 keV.
The event fluence (10-1000 keV) in this time interval is
(1.2 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+15.7 s in the 10-1000 keV band
is 2.5 +/- 0.2 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."