TITLE:   GCN CIRCULAR
NUMBER:  16648
SUBJECT: Konus-Wind observation of GRB 140729A
DATE:    14/07/31 15:14:09 GMT
FROM:    Anastasia Tsvetkova at Ioffe Institute  <tsvetkova@mail.ioffe.ru>

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

The long-duration, hard-spectrum GRB 140729A
(Fermi-LAT detection: Arimoto and Bissaldi, GCN 16633;
IPN triangulation: Hurley et al., GCN 16637)
triggered Konus-Wind at T0=2213.751 s UT (00:36:53.751).

The burst light curve shows a single pulse with a duration of ~16 s
followed by a weak tail seen up to T0+33s.
The emission is seen up to ~2 MeV.

As observed by Konus-Wind, the burst
had a fluence of 2.0(-0.2,+0.3)x10^-5 erg/cm2,
and a 64-ms peak energy flux, measured from T0+2.656 s,
of 4.5(-1.6,+1.7)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the burst
(measured from T0 to T0+16.640 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.65(-0.29,+0.36),
and Ep = 592(-122,+187) keV (chi2 = 76/89 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.7 (chi2 = 76/88 dof).

The spectrum near the peak count rate
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 2 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.68(-0.29,+0.35),
and Ep = 619(-132,+233) keV (chi2 = 51/60 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.0 (chi2 = 51/59 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB140729_T02213/

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