[vsnet-grb-info 15978] Konus-Wind observation of GRB 141229A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17260
SUBJECT: Konus-Wind observation of GRB 141229A
DATE:    14/12/31 12:06:31 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. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 141229A
(MAXI/GSC detection: Fujita et al., GCN Circ. 17246;
Fermi-GBM observation: Roberts, GCN Circ. 17249;
Swift-BAT observation: Cummings, GCN Circ. 17256)
triggered Konus-Wind at T0=42542.652 s UT (11:49:02.652).

The burst light curve shows a single pulse with a duration of ~7.6 s.
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/GRB141229_T42542/

As observed by Konus-Wind, the burst
had a fluence of 4.7(-0.6,+0.8)x10^-6 erg/cm2,
and a 64-ms peak flux, measured from T0+0.064 s,
of 4.6(-1.3,+1.3)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -1.03 (-0.22,+0.25)
and Ep = 254 (-51,+86) keV (chi2 = 82/97 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.3
(chi2 = 82/96 dof)

The spectrum near the maximum count rate
(measured from T0+0.000 to T0+0.256 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = 0.3 (-0.5,+0.7)
and Ep = 407 (-71,+101) keV (chi2 = 35/36 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.4
(chi2 = 35/35 dof)

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