TITLE:   GCN CIRCULAR
NUMBER:  19835
SUBJECT: GRB 160821A: Fermi GBM Detection
DATE:    16/08/22 04:13:58 GMT
FROM:    Matthew Stanbro at UAH/Fermi  <mcs0001@uah.edu>

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

"At 20:34:30.04 UT on 21 August 2016, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 160821A (trigger 493504474 / 160821857), which
was also detected by the Swift/BAT (Siegel et al. 2016, GCN 19830) and
by the LAT (McEnery et al. 2016, GCN 19831).
The GBM on-ground location is consistent with the Swift position.

The GBM light curve shows/consists of several episodes and
a bright burst with a duration (T90) of about 43 s (50-300 keV).
The time-averaged spectrum from T0-4.1 s to T0+194.6 s is
best fit by a Band function with Epeak = 968 +/- 16 keV,
alpha = -1.08 +/- 0.00, and beta = -2.38 +/- 0.03

The event fluence (10-1000 keV) in this time interval is
(550.3 +/- 1.39)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+135.7 s in the 10-1000 keV band
is 123.1 +/- 0.7 ph/s/cm^2.

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