[vsnet-grb-info 14971] Konus-Wind observation of GRB 140512A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16265
SUBJECT: Konus-Wind observation of GRB 140512A
DATE:    14/05/14 15:26:32 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin at mail.ioffe.ru>

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

A long-duration GRB 140512A (Swift-BAT trigger 598819: Pagani et al., 
GCN 16249; Sakamoto et al., GCN 16258; Fermi-GBM detection: Stanbro, GCN 
16262) triggered Konus-Wind at T0=70310.769 s UT (19:31:50.769).

The light curve shows two separated multipeaked episodes: the first from 
~T0-21 s to ~T0+12 s and the second longer and brighter from ~T0+88 s to 
~T0+158 s. A total duration of the burst is ~179 s.

As observed by Konus-Wind, the burst had a fluence
of 4.8(-0.8,+2.0)x10^-5 erg/cm2, and a 256-ms peak flux,
measured from T0+121.856 s, of 3.7(-1.2,+1.3)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the first bursting episode
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 1.2 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.85 (-0.47,+0.61)
and Ep = 279 (-69,+148) keV (chi2 = 62/60 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy
photon index: beta < -2.1 (chi2 = 62/59 dof).

The time-averaged spectrum of the second bursting episode
(measured from T0+90.368 to T0+155.904 s)
is best fit in the 20 keV - 6 MeV range
by a power law with exponential cutoff model with the following parameters:
alpha = -1.30 (-0.18,+0.21)
and Ep = 466 (-124, +287) keV (chi2 = 79/79 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy
photon index: beta < -1.9 (chi2 = 78/78 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB140512_T70310/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.