TITLE: GCN CIRCULAR NUMBER: 11893 SUBJECT: Konus-Wind observation of GRB 110406A DATE: 11/04/07 13:16:00 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 exceptionally bright GRB 110106A, (Savchenko et al., GCN 11890) triggered Konus-Wind at T0=13446.671s UT (03:44:06.671) The burst light curve consists of a single FRED-like pulse, the total duration of the burst is ~8 s. The emission is seen up to ~10 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB110406_T13446/ The non-zero spectral lag between the Konus-Wind light curves is evident, the following values are obtained: ------------------------------------------------------------- LC1(keV) LC2(keV) Search interval(s) Scale Lag(ms) ------------------------------------------------------------- G2(70-300) G1(18-70) -0.048:+2.016 16 ms +58 ± 6 G3(300-1160) G1(18-70) -0.016:+1.968 16 ms +127 ± 6 G3(300-1160) G2(70-300) -0.048:+2.016 16 ms +64 ± 5 ------------------------------------------------------------- As observed by Konus-Wind the burst had a fluence of (4.8 ± 0.5)x10-5 erg/cm2, and a 16-ms peak flux, measured from T0+0.160s, of (1.5 ± 0.1)x10-4 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum of the burst (from T0 to T0+9.216 s) can be fitted in the 20 keV - 10 MeV range by the GRB (Band) model, for which: the low-energy photon index alpha = -1.24 (-0.07, +0.08), the high energy photon index beta = -2.30 (-0.25, +0.15), the peak energy Ep = 326(-42, +49) keV, chi2 = 117/89 dof. The spectrum at the maximum count rate (measured from T0+0.064 to T0+0.256 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model, for which: the low-energy photon index alpha = -0.61 (-0.13, +0.15), the high energy photon index beta = -2.05 (-0.12, +0.10), the peak energy Ep = 417(-64, +77) keV, chi2 = 56.5/56 dof. All the quoted results are preliminary. The lag errors are given on 1 sigma level. All other quoted errors are at the 90% confidence level.