GCN Circular 17794

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 150430A
(Swift/BAT detection: D'Elia et al., GCN Circ. 17789
Not found
 
 
;
MAXI/GSC detection: Fujita et al., GCN Circ. 17791
Not found
 
 
;
Fermi/GBM detection: Roberts and Younes, GCN Circ. 17793
Not found
 
 
)
triggered Konus-Wind at T0=1271.466 s UT (00:21:11.466).

The burst light curve shows three well separated emission episodes:
a weak episode at T-T0 ~ -320 s, the main episode at T-T0 ~ 0 s,
and a weak episode at T-T0 ~ 100 s.
The total burst duration is about 420 s.
There is a hint of soft precursor at T-T0 ~ -440 s.
The emission is seen up to ~5 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB150430_T01271/

As observed by Konus-Wind, the burst
had a fluence of 2.95(-0.75,+1.14)x10^-5 erg/cm2,
and a 256-ms peak flux, measured from T0+1.248 s,
of 4.11(-1.02,+1.09)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the main episode
(measured from T0 to T0+114.944 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 = -0.79(-0.69,+1.48),
the high energy photon index beta = -2.21(-0.66,+0.33),
the peak energy 157(-70,+93) keV
(chi2 = 69/72 dof)

The spectrum near the maximum count rate
(measured from T0+0.000 to T0+8.448 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 = -0.47(-0.35,+0.45),
the high energy photon index beta = -2.11(-0.24,+0.16),
the peak energy 194(-38,+54) keV
(chi2 = 80/97 dof)

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