TITLE: GCN CIRCULAR NUMBER: 33061 SUBJECT: Konus-Wind detection of GRB 221209A DATE: 22/12/15 16:36:16 GMT FROM: Dmitry Frederiks at Ioffe Institute D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: The long GRB 221209A (Fermi-GBM observation: Bissaldi, GCN 33034; AstroSat CZTI detection: Gopalakrishnan et al., GCN Circ 33037; IPN triangulation: Kozyrev et al., GCN 33059) triggered Konus-Wind (KW) at T0=21024.993 s UT (05:50:24.993). The burst light curve shows a bright, FRED-like pulse, which starts at ~T0-0.5 s, peaks at ~T0-0.640 s, and has a total duration of ~10 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/GRB221209_T21024/ As observed by Konus-Wind, the burst had a fluence of (6.39 �� 0.43)x10^-5 erg/cm^2 and a 64-ms peak energy flux, measured from T0 + 0.640 s, of (4.89 �� 0.28)x10^-5 erg/cm^2/s (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum (measured from T0 to T0+12.302 s) is best fit in the 20 keV - 15 MeV range by a GRB (Band) function with the following model parameters: the low-energy photon index alpha = -0.64 (-0.09,+0.10), the high energy photon index beta = -2.05 (-0.08,+0.07), the peak energy Ep = 306 (-32,+36) keV, chi2 = 103/97 dof. The spectrum near the peak count rate (measured from T0+0.256 to T0+1.280 s) is best fit in the 20 keV - 15 MeV range by a GRB (Band) function with the following model parameters: the low-energy photon index alpha = -0.28 (-0.11,+0.12), the high energy photon index beta = -1.97 (-0.07,+0.06), the peak energy Ep = 366 (-39,+46) keV, chi2 = 68/66 dof. All the quoted errors are estimated at the 90% confidence level. All the presented results are preliminary.