[vsnet-grb-info 18395] GRB 160821B: Fermi GBM Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  19843
SUBJECT: GRB 160821B: Fermi GBM Detection
DATE:    16/08/22 20:18:16 GMT
FROM:    Matthew Stanbro at UAH/Fermi  <mcs0001 at uah.edu>

M. Stanbro (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 22:29:13.33 UT on 21 August 2016, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 160821B (trigger 493511357 / 160821937), which
was also detected by the Swift/BAT (Siegel et al. 2016, GCN 19833)
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 61
degrees.

The GBM light curve consists of a few episodes
with a duration (T90) of about 1 s (50-300 keV).
The time-averaged spectrum from T0-0.13 s to T0+0.32 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.37 +/- 0.22 and
the cutoff energy, parameterized as Epeak, is 84 +/- 19 keV

The event fluence (10-1000 keV) in this time interval is
(1.68 +/- 0.19)E-06 erg/cm^2. The 64-millisec peak photon flux measured
starting from T0+0.00 s in the 10-1000 keV band
is 9.16 +/- 1.19 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."