TITLE: GCN CIRCULAR NUMBER: 9968 SUBJECT: Konus-RF observation of GRB 090929A DATE: 09/09/29 17:45:37 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, P. Oleynik, M. Ulanov, and D. Svinkin on behalf of the Konus-RF team, report: The bright GRB 090929A (Fermi-GBM trigger trigger 275891585: Rau, GCN 9962) localized by Swift-BAT (Cummings and Krimm , GCN 9966) triggered Konus-RF at T0=16384.747 s UT (04:33:04.747). The burst light curve shows several multipeaked pulses with a total duration of ~6 s. As observed by Konus-RF the burst had a fluence of 1.24(-0.11, +0.12)x10^-5 erg/cm2, and a 16-ms peak flux measured from T0-0.040 s of (2.02 +/- 0.46)x10^-5 erg/cm2/s (both in the 20 keV - 3 MeV energy range). The time-integrated spectrum of the burst (from T0-1.2 to T0+4.5 s) is well fitted (in the 10 keV - 3 MeV range) by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep), with alpha = -0.55(-0.11, +0.12), and Ep = 480(-54, +64) keV (chi2 = 120.1/119 dof). The spectrum accumulated over the burst maximum (from T0-0.2 to T0+0.1 s) is well fitted (in the 10 keV - 3 MeV range) by a power law with exponential cutoff model with alpha = -0.28(-0.14, +0.15), and Ep = 633(-71, +81) keV (chi2 = 44.0/56 dof). Fitting by GRB (Band) model yields the same alpha and Ep, and only an upper limit on the high energy photon index: beta < -3.06 (chi2 = 44.0/55 dof). All the quoted values are preliminary. All the quoted errors are at the 90% confidence level. The Konus-RF light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB090929_T16384/KRF/