TITLE: GCN CIRCULAR NUMBER: 10276 SUBJECT: Konus-Wind observation of GRB 091208A DATE: 09/12/10 16:47:11 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report: The long GRB 091208A (Swift-BAT trigger #378554: Hoversten et al., GCN 10253; Barthelmy et al., GCN 10264) triggered Konus-Wind at T0=31563.038s UT (08:46:03.038). The burst light curve shows a smooth single-pulse structure with a total duration of ~30 s. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB091208_T31563/ As observed by Konus-Wind the burst had a fluence of 6.2(+/-1.0)x10-6 erg/cm2, and a 256-ms peak flux measured from T0-0.256s of 1.3(+/-0.2)x10-6 erg/cm2/s (both in the 20 keV - 2 MeV energy range). The time-integrated spectrum of the burst (from T0 to T0+24.832 s) can be fitted 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 = +0.24(-0.5, +0.7), and Ep = 314(-50, +70) keV (chi2 = 74/61 dof). The spectrum of the most intense part of the burst (measured from T0 to T0+8.448 s) is well fitted in the 20 keV - 2 MeV range by a power law with exponential cutoff model, for which alpha = +0.13(-0.4, +0.55), and Ep = 316(-44, +60) keV (chi2 = 47/61 dof). All the quoted results are preliminary. All the quoted errors are at the 90% confidence level.