TITLE:   GCN CIRCULAR
NUMBER:  34846
SUBJECT: Konus-Wind detection of GRB 231018A
DATE:    23/10/19 18:44:04 GMT
FROM:    Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>

D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin,
Yu. Temiraev, A. Tsvetkova,  M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:

The long, bright GRB 231018A (Fermi GBM detection: Lesage et al., GCN 34831;
IPN triangulation: Svinkin et al., GCN 34845)
triggered Konus-Wind (KW) at T0=45043.083 s UT (12:30:43.083).

The burst light curve shows a multi-peaked emission complex,
which starts at ~T0-32 s, peaks at ~T0+28 s,
and has a total duration of ~90 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/GRB231018_T45043/

As observed by Konus-Wind, the burst had
a fluence of (1.17 ± 0.04)x10^-4 erg/cm^2 and
a 64-ms peak energy flux, measured from T0 + 28.352 s,
of (2.44 ± 0.10)x10^-5 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+38.912 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 = -1.34 (-0.05,+0.05),
the high energy photon index beta = -2.92 (-0.17,+0.12),
the peak energy Ep = 114 (-4,+4) keV,
chi2 = 90/96 dof.

The spectrum near the peak count rate (measured from T0+24.576 to T0+29.696 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 = -1.19 (-0.05,+0.06),
the high energy photon index beta = -3.15 (-0.37,+0.24),
the peak energy Ep = 146 (-7,+8) keV,
chi2 = 67/73 dof.

All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.