GCN Circular 18081
Subject
GRB 150727A: Fermi GBM detection
Date
2015-07-28T06:25:51Z (9 years ago)
From
George A. Younes at George Washington U <gyounes@email.gwu.edu>
G. Younes (GWU) reports on behalf of the Fermi GBM Team:
"At 19:01:56.35 UT on July 27 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 150727A (trigger 459716520/150727793), which
was also detected by Swift (Cenko et al. 2015, GCN 18076). The GBM
on-ground location, using the Fermi GBM trigger data, is consistent
with the Swift/XRT location.
The angle of the burst direction to the Fermi LAT boresight
is 46 degrees.
The GBM light curve shows a FRED-like (fast-rise exponential-decay)
pulse with a duration (T90) of about 50s (50-300 keV). The
time-averaged spectrum from T0-4s to T0+56s is well fit by a power
law with an exponential high-energy cutoff. The power law index is
-0.7 +/- 0.1 and the cutoff energy, parameterized as Epeak, is 149 +/-
10 keV.
The event fluence (10-1000 keV) in this time interval is
(7.9 +/- 0.3)E-06 ergs/cm^2. The 1.0-sec peak photon flux measured
starting from T0+5.0s in the 10-1000 keV band
is 2.1 +/- 0.2 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."