GCN Circular 17870

S. Golenetskii, R. Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 150523A
(Fermi-GBM detection: Yu, GCN Circ. 17863
Not found
 
 
;
Fermi-LAT detection: Bissaldi, et al., GCN Circ. 17864
Not found
 
 
)
triggered Konus-Wind at T0=34189.641 s UT (09:29:49.641).

The burst light curve consists of two pulses
with a total duration of ~36 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/GRB150523_T34189/

As observed by Konus-Wind, the burst
had a fluence of 4.44(-0.69,+0.71)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+31.792 s,
of 5.52(-1.52,+1.53)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+41.216 s)
is best fit in the 20 keV - 12 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.31(-0.14,+0.16),
the high energy photon index beta = -2.66(-0.99,+0.32),
the peak energy 399(-42,+52) keV
(chi2 = 94/97 dof)

The spectrum near the maximum count rate
(measured from T0+24.832 to T0+33.024 s)
is best fit in the 20 keV - 12 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.35(-0.15,+0.17),
the high energy photon index beta = -2.66(-1.35,+0.34),
the peak energy 389(-48,+58) keV
(chi2 = 104/97 dof)

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