[vsnet-grb-info 15392] GRB140809A: Fermi GBM observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16681
SUBJECT: GRB140809A: Fermi GBM observation
DATE:    14/08/11 11:55:43 GMT
FROM:    Oliver Roberts at UCD/Fermi  <oliver.roberts at ucd.ie>

Oliver Roberts (UCD) and Véronique Pelassa (UAH)
reports on behalf of the Fermi GBM Team:

"At 03:11:10.20 UT on the 9th of August 2014, the Fermi Gamma-Ray
Burst Monitor triggered and located GRB 140809A
(trigger 429246673 / 140809133), for which a possible optical
transient was also detected by the MASTER II robotic telescope
(Lipunov et al. 2014, GCN 16674). The GBM on-ground location is
consistent with the OT position. The angle from the Fermi LAT
boresight is 40 degrees.

The GBM light curve consists of one bright pulse, followed by
a sequence of shorter, dimmer pulses with a duration (T90) of
about 70s (50-300 keV). The time-averaged spectrum from
T0-14.6 s to T0+70.1 s is adequately fit by a power law
function with an exponential high-energy cutoff. The power law
index is -0.99 +/- 0.14  and the cutoff energy, parameterised as
Epeak, is 507 +/- 192 keV.

The event fluence (10-1000 keV) in this time interval is
(2.10 +/- 0.04)E-06 erg/cm^2. The 1.024-sec peak photon flux
measured starting from T0+1.28 s in the 10-1000 keV band is
1.39 +/- 0.18 ph/s/cm^2.

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