TITLE: GCN CIRCULAR NUMBER: 38537 SUBJECT: Konus-Wind detection of GRB 241209B DATE: 24/12/11 15:50:35 GMT FROM: Anna Ridnaia at Ioffe Institute ridnaia@mail.ioffe.ru
A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report:
The long-duration GRB 241209B (SVOM/ECLAIRs and GRM detection: Xie et al., GCN 38478; Swift/BAT-GUANO localization: DeLaunay et al., GCN 38528; GRBAlpha detection: Dafcikova et al., GCN 38534) triggered Konus-Wind at T0=14182.105 s UT (03:56:22.105).
The burst light curve shows a single pulse, which starts at ~T0-0.480 s and has a total duration of ~0.7 s.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB241209_T14182/
As observed by Konus-Wind, the burst had a fluence of 4.45(-0.41,+1.38)x10^-7 erg/cm2, and a 16-ms peak flux, measured from T0-0.318 s, of 1.66(-0.55,+0.74)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
Since the brightest peak of the burst light curve was detected before the trigger, the spectral analysis was performed using the KW 3-channel light curve data.
Modelling the KW 3-channel time-integrated spectrum (measured from T0-0.480 s to T0+0.174 s) by a power law with exponential cutoff (CPL) model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep), yields alpha = -0.21(-0.40,+1.27) and Ep = 163(-48,+45) keV.
All the quoted errors are at the 68% confidence level. All the quoted values are preliminary.
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