TITLE: GCN CIRCULAR NUMBER: 12078 SUBJECT: Konus-Wind observation of GRB 110618A DATE: 11/06/23 10:21:30 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 hard GRB 110618A (localized by IPN: Hurley et al., GCN 12077) triggered Konus-Wind at T0=31673.867 s UT (08:47:53.867) The burst light curve consists of a single long hard pulse with unusually gentle onset and a total duration of ~250 s. The emission is seen up to ~5 MeV, a hard-to-soft spectral evolution is noticeable in the course of the event. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB110618_T31673/ As observed by Konus-Wind the burst had a fluence of (1.1 ± 0.1)x10-4 erg/cm2, and a 256-ms peak flux, measured from T0+1.280 s, of (2.0 ± 0.2)x10-6 erg/cm2/s (both in the 20 keV - 5 MeV energy range). The time-integrated spectrum of the burst (measured from T0 to T0+229.632 s) is best fitted in the 20 keV - 5 MeV range by a power law with exponential cutoff model, for which alpha = -1.40 (-0.08, +0.10), and Ep = 569(-160, +304) keV, chi2 = 78.1/73 dof. The spectrum at the maximum count rate (measured from T0 to T0+8.448 s) can be fitted in the 20 keV - 5 MeV range by a power law with exponential cutoff model, for which alpha = -1.12 (-0.06, +0.06), and Ep = 524(-96, +138) keV, chi2 = 88.7/73 dof. All the quoted results are preliminary. All the quoted errors are at the 90% confidence level.