TITLE:   GCN CIRCULAR
NUMBER:  25218
SUBJECT: Konus-Wind observation of GRB 190727B
DATE:    19/07/29 16:14:05 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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

The long-duration GRB 190727B
(Swift-BAT detection: Lien et al., GCN Circ. 25176;
Fermi-GBM observations: Veres and Meegan, GCN Circ. 25180;
Fermi-LAT detection: Kovacevic et al., GCN Circ. 25186)
triggered Konus-Wind at T0=73072.783 s UT (20:17:52.783).

The burst light curve shows a multi-peaked structure
which starts at ~T0-3.8 s and has a total duration of ~62 s.
The emission is seen up to ~6 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB190727_T73072/

As observed by Konus-Wind, the burst
had a fluence of 9.92(-1.04,+1.04)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+21.040 s,
of 1.82(-0.34,+0.33)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+44.800 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.11(-0.07,+0.07),
the high energy photon index beta = -2.27(-0.29,+0.16),
the peak energy Ep = 402(-49,+64) keV
(chi2 = 106/97 dof).

The spectrum near the maximum count rate
(measured from T0+16.640 to T0+21.504 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.07(-0.08,+0.09),
the high energy photon index beta = -2.38(-0.85,+0.24),
the peak energy Ep = 566(-98,+136) keV
(chi2 = 94/97 dof).

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