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.