TITLE:   GCN CIRCULAR
NUMBER:  22360
SUBJECT: Konus-Wind observation of GRB 171209A
DATE:    18/01/17 13:39:48 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova@mail.ioffe.ru>

A.Kozlova, S. Golenetskii, R.Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko,
and T. Cline on behalf of the Konus-Wind team, report:

The long GRB 171209A (Swift-BAT trigger #796100: LaPorte et al.,
GCN 22213; Cummings et al., GCN 22229)
was detected by Konus-Wind (KW) in the waiting mode.

The burst light curve shows a multi-peaked structure
with a duration of ~ 147 s.

As observed by KW, the burst had a fluence of
1.56(-0.17,+0.16)x10^-5 erg/cm2 and a 2.944-s peak flux,
measured from ~T0(BAT)+22.4 s, of 3.06(-0.62,+0.61)x10^-7 erg/cm2/s
(both in the 20 - 10000 keV energy range).

Modeling the KW 3-channel time-integrated spectrum
(from ~T0(BAT)-1.2 s to ~T0(BAT)+146 s)
by a power law with exponential cutoff model
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
yields alpha = -1.13 (-0.23,+0.40), and Ep = 279 (-86,+141) keV.

The KW light curve of this burst is available at
http://www.ioffe.rssi.ru/LEA/GRBs/GRB171209A/

All the quoted errors are estimated at the 1 sigma confidence level.
All the presented results are preliminary.