TITLE:   GCN CIRCULAR
NUMBER:  15818
SUBJECT: Konus-Wind observation of GRB 140209A
DATE:    14/02/11 17:13:12 GMT
FROM:    Valentin Pal'shin at Ioffe Inst  <val@mail.ioffe.ru>

S. Golenetskii, R.Aptekar, V. Pal'shin, D. Frederiks, P. Oleynik, M.
Ulanov, D. Svinkin, A. Tsvetkova and T. Cline on behalf of the
Konus-Wind team report:

The bright GRB 140209A (Swift-BAT trigger #586071: Cenko et al., GCN 
15808, Palmer et al., GCN 15812; Fermi-GBM detection: von Kienlin, GCN 
15811) triggered Konus-Wind at T0=27060.493 s UT (07:31:00.493).

The burst light curve shows a double peaked pulse with a total duration 
of ~1.4 s. The emission is seen up to ~1 MeV.

As observed by Konus-Wind, the burst had a fluence of (7.2 ± 0.6)x10^-6 
erg/cm2, and a 16-ms peak flux, measured from T0+0.280 s,
of (2.2 ± 0.3)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+8.448 s)
is best fit (in the 20 keV - 1 MeV range)
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -1.09(-0.21,+0.23)
and Ep = 173(-20,+15) keV (chi2 = 53.2/55 dof).
Fitting by GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy
photon index: beta < -2.8 (chi2 = 53.2/54 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB140209_T27060/

All the quoted errors are at the 90% confidence level.

All the quoted results are preliminary.