[vsnet-grb-info 16604] Konus-Wind observation of GRB 150527A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17885
SUBJECT: Konus-Wind observation of  GRB 150527A
DATE:    15/05/28 17:00:31 GMT
FROM:    Anastasia Tsvetkova at Ioffe Institute  <tsvetkova 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 150527A (Swift-BAT trigger #641698:
Evans, et al., GCN Circ. 17874; Lien, et al., GCN Circ. 17880;
Fermi-GBM detection: Yu, GCN Circ.17878)
was detected by Konus-Wind in the waiting mode.

The burst light curve shows two emission episodes:
the first episode (from ~T0(BAT)-108 s to ~T0(BAT)-99 s) triggered GBM,
and the second (from ~T0(BAT)-22 s to ~T0(BAT)+4s), which triggered BAT.

As observed by Konus-Wind, the burst had a fluence of
6.09(-0.62,+0.76)x10^-6 erg/cm2 and a 2.944-s peak flux,
measured from ~T0(BAT)-13 s, of 3.10(-0.61,+0.65)x10^-7 erg/cm2/s
(both in the 20 - 1000 keV energy range).

Fitting the K-W 3-channel time-integrated spectrum
(measured from ~T0(BAT)-108 s to ~T0(BAT)+4 s)
by a simple power-law model yields the photon index
-2.20(-0.10,+0.10), chi2=0.88/1 dof.

Modelling the 3-channel spectrum near the peak count rate
(from ~T0(BAT)-13 s to ~T0(BAT)-10 s)
by the cutoff power law yields the following model parameters:
the photon index alpha = -1.62(-0.31,+0.92),
and the peak energy Ep = 107(-40,+100) 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/GRB150527A/