TITLE:   GCN CIRCULAR
NUMBER:  22746
SUBJECT: Konus-Wind observation of GRB 180526A
DATE:    18/05/29 15:06:21 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova@mail.ioffe.ru>

A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 180526A
(AstroSat CZTI detection: Sharma et al., GCN 22742;
CGBM detection: Matsukawa et al., GCN 22744;
IPN Triangulation: Hurley et al., GCN 22745)
triggered Konus-Wind at T0=39816.006 s UT (11:03:36.006).

The burst light curve shows a multipeaked structure
started at ~T0-9 s with a total duration of ~87 s.
The emission is seen up to ~4 MeV.

As observed by Konus-Wind, the burst
had a fluence of 1.12(-0.13,+0.13)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+42.048 s,
of 1.61(-0.28,+0.29)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+76.032 s)
is best fit in the 20 keV - 4 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.11(-0.13,+0.15),
the high energy photon index beta = -2.23(-0.24,+0.14),
the peak energy Ep = 207(-31,+38) keV
(chi2 = 76/69 dof).

The spectrum near the maximum count rate
(measured from T0+41.216 to T0+43.264 s)
is best fit in the 20 keV - 4 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.52(-0.17,+0.19),
the high energy photon index beta = -2.49(-0.31,+0.20),
the peak energy Ep = 224(-25,+27) keV
(chi2 = 56/58 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180526_T39816/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.