TITLE:   GCN CIRCULAR
NUMBER:  46196
SUBJECT: Konus-Wind detection of GRB 261024A
DATE:    26/11/08 18:12:15 GMT
FROM:    Valentina Panteleeva at Ioffe Institute <panteleevav228@gmail.com>

V. Panteleeva, 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-duration GRB 261024A
(Fermi-GBM detection: The Fermi GBM team, GCN 46019;
BALROG localization: Preis & Greiner, GCN 46020;
NuSTAR detection: Waratkar & Grefenstette, GCN 46031;
SVOM-GRM observation: Luo et al., GCN 46057;
IPN triangulation: Kozyrev et al., GCN 46156)
triggered Konus-Wind at T0=58983.054 s UT (16:23:03.054).

The burst light curve shows a multipeaked structure
which starts at ~T0-1.3 s and has a total duration of ~17.4 s.
The emission is seen up to ~600 keV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB261024_T58983/

As observed by Konus-Wind, the burst
had the total fluence of 9.59(-0.27,+0.28)x10^-6 erg/cm2,
and the 64-ms peak flux, measured from T0+4.752 s,
of 2.93(-0.40,+0.40)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -1.04(-0.06,+0.07)
and Ep = 127(-5,+5) keV (chi2 = 87/86 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -4.17
(chi2 = 87/85 dof).

All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.