[vsnet-grb-info 12936] Konus-Wind observation of GRB 130306A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14275
SUBJECT: Konus-Wind observation of GRB 130306A
DATE:    13/03/08 16:33:09 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 very long-duration GRB 130306A
(Swift-BAT trigger #550457: Siegel et al., GCN 14266;
Fermi-GBM observation: Pelassa, GCN 14270)
triggered Konus-Wind at T0=85669.636s UT (23:47:49.636)

The light curve shows a multi-pulse emission which
started ~270 s before the trigger, peaked at ~T0+10s,
and, after ~T0+110s, passed into a long tail
out to ~400 s after the trigger.
The total duration of the burst is ~700 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/GRB130306_T85669/

As observed by Konus-Wind, the burst
had a fluence of (2.9 ± 0.05)x10-4 erg/cm2,
and a 64-ms peak flux, measured from T0+8.768 s,
of (6.1 ± 0.6)x10-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum
(measured from T0 to T0+116.224 s)
is best fit in the 20 keV - 5 MeV range
by a power law with exponential cutoff model,
for which:
alpha = -1.50 ± 0.05,
and Ep = 212 ± 10 keV,
chi2 = 53.8/59 dof.

The spectrum at the maximum count rate
(measured from T0 to T0+11.774 s)
is best fit in the 20 keV - 5 MeV range
by a power law with exponential cutoff model,
for which:
alpha = -1.34 ± 0.04,
and Ep = 410 ± 30 keV,
chi2 = 64.7/71 dof.

The spectrum of the emission tail
(measured from T0+116.224 to T0+402.944 s)
is best fit in the 20 keV - 5 MeV range
by the simple power-law model with
the photon index -2.3 ± 0.1, chi2 = 65.1/75 dof.
The emission in this time interval is seen up to 4 MeV
and the 20 keV - 10 MeV energy fluence
is (2.7 ± 0.3)x10-5 erg/cm2.

All the quoted results are preliminary.