[vsnet-grb-info 13386] Konus-Wind observation of GRB 130527A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14720
SUBJECT: Konus-Wind observation of GRB 130527A
DATE:    13/05/29 14:11:48 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 intense hard-spectrum GRB 130527A
(Swift-BAT trigger 556753: Gompertz et al., GCN 14703;)
Baumgartner et al., GCN 14708)
triggered Konus-Wind at T0=51688.300s UT (14:21:28.300).

The light curve shows a bright hard multi-peaked
emission complex from ~T0 s to ~T0+10s,
followed by the weaker and softer emission out to ~T0+40s.

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/GRB130527_T51688/

As observed by Konus-Wind, the burst
had a fluence of (1.1 ± 0.05)x10-4 erg/cm2,
and a 64-ms peak flux, measured from T0+3.200s,
of (5.0 ± 0.3)x10-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+38.656 s)
is best fit in the 50 keV - 15 MeV range
by the cutoff power law model with the following parameters:
the photon index alpha = -1.04 ± 0.04,
the peak energy Ep = 1380 ± 120 keV,
chi2 = 96/90 dof.

The spectrum at the maximum count rate
(measured from T0+0.256 to T0+5.888 s)
is best fit in the 50 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
by the cutoff power law model with the following parameters:
the photon index alpha = -0.97 ± 0.04,
the peak energy Ep = 1429 ± 84 keV,
chi2 = 72/79 dof.

All the quoted results are preliminary.