[vsnet-grb-info 12991] Konus-Wind observation of GRB 130320A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14328
SUBJECT: Konus-Wind observation of GRB 130320A
DATE:    13/03/24 12:28:11 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 intense long-duration GRB 130320A
(IPN triangulation: Hurley et al., GCN 14327)
triggered Konus-Wind at T0=25724.822s UT (07:08:44.822)

The light curve shows a double-peaked pulse with a total
duration of ~20 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/GRB130320_T25724/
Note: periodic "dips" visible in this light curve are due
to the GRB source occultation by the spacecraft structure.

As observed by Konus-Wind, the burst
had a fluence of (2.6 ± 0.05)x10-5 erg/cm2,
and a 64-ms peak flux, measured from T0+0.960 s,
of (1.85 ± 0.1)x10-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum
(measured from T0 to T0+22.784 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model,
for which:
alpha = -0.78 ± 0.05,
and Ep = 295 ± 7 keV,
chi2 = 85.0/93 dof.

The spectrum at the maximum count rate
(measured from T0 to T0+2.048 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model,
for which:
alpha = +0.27 ± 0.06,
and Ep = 364 ± 7 keV,
chi2 = 91.1/98 dof.

All the quoted results are preliminary.