[vsnet-grb-info 16521] Konus-Wind observation of GRB 150428A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17802
SUBJECT: Konus-Wind observation of GRB 150428A
DATE:    15/05/04 14:55:51 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin at mail.ioffe.ru>

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 150428A (Swift-BAT trigger #639275:
Page, et al., GCN Circ. 17765; Baumgartner, et al., GCN Circ. 17774)
was detected by Konus-Wind in the waiting mode.

The burst light curve shows a single pulse which started approximately 
at BAT trigger time T0(BAT) and has a duration of ~45 s.

As observed by Konus-Wind, the burst had a fluence of
1.61(-0.09,+0.10)x10^-5 erg/cm2 and a 2.944-s peak flux,
measured from ~T0(BAT)+21 s, of 5.5(-0.7,+0.9)x10^-7 erg/cm2
(both in the 20 - 1200 keV energy range).

Modelling the K-W 3-channel time-integrated spectrum (from T0(BAT)-3 s
to T0(BAT)+41 s) by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
yields alpha = -1.04(-0.12,+0.14), and Ep = 275(-29,+37) keV.

All the quoted errors are estimated at the 1 sigma confidence level.
All the presented results are preliminary.

The K-W light curve of this burst is available at
http://www.ioffe.rssi.ru/LEA/GRBs/GRB150428A/