TITLE: GCN CIRCULAR NUMBER: 8611 SUBJECT: Konus-Wind observation of GRB 081203A DATE: 08/12/04 16:01:56 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, P. Oleynik, D. Svinkin, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team report: The long GRB 081203A (Parsons et al., GCN 8595, Ukwatta et al., GCN 8599) was detected by Konus-Wind in the same trigger record as GRB 081203B (Copete et al., GCN 8600, 8602; Golenetskii et al., GCN 8610) at ~T0(KW)+260s. (T0(KW)=49890.368 s UT (13:51:30.368). Correcting for the propagation time delay from Wind to Swift of 0.7s, one sees that T0(BAT) corresponds to T0(KW)+339.9s). Since this burst occurred after the end of the time history record (=T0(KW)+229s) we do not have the light curve of this GRB with good time resolution. Instead we have KW multichannel spectra accumulated until T0(KW)+490s (that is until T0(BAT)+150s), which were converted to a 3-band light curve with a time resolution of 8.192 s. The burst light curve shows a weak emission starting at ~T0(BAT)-80s (=T0(KW)+260s), the main double-peaked pulse starting at ~T0(BAT)-14s (=T0(KW)+326s) and the decaying tail seen at least until T0(BAT)+134s (=T0(KW)+474s). As observed by Konus-Wind the burst had a fluence of 3.05(-0.89, +1.40)x10^-5 erg/cm2 (in the 20 keV - 3 MeV energy range). The time-integrated spectrum of the burst (from T0(BAT)-79s to T0(BAT)+134 s) is well fitted (in the 20 keV-3 MeV range) by a simple power law model with index 1.54 +/- 0.08 (chi2 = 65.8/69 dof). Fitting by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) yields alpha = -1.33(-0.20, +0.27) and Ep = 578(-290, +2398) keV (chi2 = 61.2/68 dof). The spectrum of the main pulse (from T0(BAT)-14s to T0(BAT)+52s) is well fitted (in the 20 keV-3 MeV range) by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.29(-0.13, +0.15) and Ep = 497(-156, +383) keV (chi2 = 66.2/68 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/GRB081203A/