TITLE: GCN CIRCULAR NUMBER: 9975 SUBJECT: Konus-Wind observation of GRB 090929B DATE: 09/09/30 13:30:14 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report: The long GRB 090929B (Swift-BAT trigger #371050: Pagani et al., GCN 9963) triggered Konus-Wind at T0=36565.377 s UT (10:09:25.377). The burst light curve shows a multipeaked structure with a total duration of ~20 s. As observed by Konus-Wind the burst had a fluence of (1.16 +/- 0.12)x10^-5 erg/cm2, and a 256-ms peak flux measured from T0+16.208 s of (3.80 +/- 0.90)x10^-6 erg/cm2/s (both in the 20 keV - 1 MeV energy range). The time-integrated spectrum of the burst (from T0 to T0+16.640 s) is well fitted (in the 20 keV - 1 MeV range) by GRB (Band) model for which: the low-energy photon index alpha = -0.41 (-0.77, +1.16), the high energy photon index beta = -1.82(-0.59, +0.24), the peak energy Ep = 282(-78, +169) keV (chi2 = 52.4/59 dof). All the quoted errors are at the 90% confidence level. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB090929_T36565/