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GCN Circular 14575

Subject
Konus-Wind observation of GRB 130505A
Date
2013-05-05T19:19:22Z (11 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@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 very intense GRB 130505A (Swift-BAT trigger #555136:
Cannizzo et al., GCN 14564) triggered Konus-Wind (K-W)
at T0=30147.038s UT (08:22:27.038).

The K-W light curve shows a bright pulse with a duration of ~5s
followed by a weaker decaying emission out to ~T0+30s with
a slight increase in the count rate at ~T0+15s.
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/GRB130505_T30147/

As observed by Konus-Wind, the main phase of the burst had
a fluence of (3.13 � 0.06)x10^-4 erg/cm2 and a 64-ms peak flux,
measured from T0+2.496 s, of (6.9 � 0.3)x10^-5 erg/cm2/s
(both in the 20 - 1200 keV energy range).

The time-averaged spectrum (measured from T0 to T0+21.248 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 = -0.69 � 0.04,
the high energy photon index beta = -2.03 � 0.03,
the peak energy Ep = 631 � 31 keV,
chi2 = 113/92 dof.

The spectrum at the maximum count rate
(measured from T0+2.304 to T0+2.816 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 = -0.31 � 0.09,
the high energy photon index beta = -2.26 � 0.07,
the peak energy Ep = 604 � 49 keV,
chi2 = 105/90 dof.

Assuming z=2.27 (Tanvir et al., GCN 14567)
and a standard cosmology model with H_0 = 70 km/s/Mpc,
Omega_M = 0.27, and Omega_Lambda = 0.73,
the isotropic energy release E_iso is ~3.8x10^54 erg,
the peak luminosity (L_iso)_max is ~2.7x10^54 erg/s,
and the rest-frame peak energy Ep,i = 2030 keV

All the quoted errors are estimated at the 1 sigma confidence level.
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