[vsnet-grb-info 13388] Konus-Wind observation of GRB 130528A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14722
SUBJECT: Konus-Wind observation of GRB 130528A
DATE:    13/05/29 15:33:52 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred at mail.ioffe.ru>

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

The long-duration GRB 130528A
(Swift-BAT trigger 556870: D'Elia et al., GCN 14711;
Cummings et al., GCN 14718)
triggered Konus-Wind at T0=60085.301s UT (16:41:25.301).

The light curve shows a pulse from ~T0-5 s to ~T0+10s,
followed by weaker and softer emission out to ~T0+60s.

The emission is seen up to 7 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB130528_T60085/

As observed by Konus-Wind, the burst
had a fluence of (8.0 ± 0.7)x10-6 erg/cm2,
and a 64-ms peak flux, measured from T0+0.640s,
of (1.7 ± 0.2)x10-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+57.600 s)
is best fit in the 20 keV - 15 MeV range
by the cutoff power law model with the following parameters:
the photon index alpha = -1.30 ± 0.15,
the peak energy Ep = 93 ± 9 keV,
chi2 = 90/98 dof.

The spectrum at the maximum count rate
(measured from T0+0.256 to T0+5.888 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.21 ± 0.23,
the high energy photon index beta = -2.6 ± 0.3,
the peak energy Ep = 142 ± 14 keV,
chi2 = 70/97 dof.

All the quoted results are preliminary.