GCN Circular 17422

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 150202B
(Fermi LAT detection: Axelsson and Vianello, GCN 17385
Not found
 
 
;
Fermi GBM detection: Pelassa, GCN 17388
Not found
 
 
;
IPN triangulation: Hurley et al., GCN 17398
Not found
 
 
)
triggered Konus-Wind at T0=86354.293 s UT (23:59:14.293).

The KW light curve shows a bright main pulse lasting about 15 s,
which is followed by a fainter second episode which
started at ~T0+100 s and lasted up to ~T0+210 s.
The emission in the main pulse is seen up to 10 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB150202_T86354/

As observed by Konus-Wind, the burst
had a fluence of 4.56(-0.51,+0.67)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+3.600 s,
of 1.07(-0.20,+0.20)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the main pulse
(measured from T0 to T0+12.544 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.75(-0.11,+0.14),
the high energy photon index beta = -2.39(-0.22,+0.15),
the peak energy 234(-26,+27) keV
(chi2 = 88/89 dof)

The spectrum near the maximum count rate
(measured from T0 to T0+5.888 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.69(-0.17,+0.21),
the high energy photon index beta = -2.18(-0.19,+0.12),
the peak energy 240(-38,+49) keV
(chi2 = 79/79 dof)

The time-averaged spectrum of the second episode
(measured from T0+94.464 to T0+209.152 s)
is best fit in the 20 keV - 5 MeV range
by a power law with spectral index = -1.95(-0.19,+0.21)
(chi2 = 77/78 dof).

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