TITLE:   GCN CIRCULAR
NUMBER:  9703
SUBJECT: Konus-RF and Konus-Wind observations of GRB 090718B
DATE:    09/07/24 11:08:04 GMT
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, and D. Svinkin on behalf of
the Konus-Wind and Konus-RF teams, and
T. Cline on behalf of the Konus-Wind team, report:

The long GRB 090718B (Fermi/GMM trigger 269633864/09071876;
A.J. van der Horst, GCN 9690)
triggered Konus-RF instrument onboard CORONAS-PHOTON s/c
at T0=65863.878 s UT (18:17:43.878),
and Konus-Wind
at T0=65882.144 s UT (18:18:02.144),

The burst light curve shows a smooth structure
with a duration of ~35 s. The Konus-RF and Konus-Wind
light curves of this GRB are available at
http://www.ioffe.ru/LEA/GRBs/GRB090718_T65882/

As observed by Konus-RF the burst
had a fluence of 2.6(-0.13, +0.13)x10-5 erg/cm2,
and a 64-ms peak flux measured from T0+20.904 s
of 5.0(-0.24, +0.24)x10-6 erg/cm2/s
(both in the 20 keV - 1 MeV energy range).

The time-integrated spectrum of the burst
(from T0-2.0 to T0+34.0 s) is well fit
(in the 20 keV - 1 MeV range) by GRB (Band) model
for which:
the low-energy photon index alpha = -1.3 ± 0.1,
the high energy photon index beta = -4.6( < -2.2),
the peak energy Ep = 250(-50, +35) keV (chi2 = 126/106 dof).

The spectrum of the burst at the maximum count rate
(from T0+20.5 to T0+21.0 s) is well fit
(in the 20 keV - 1 MeV range) by GRB (Band) model
for which:
the low-energy photon index alpha = -0.83 ± 0.13,
the high energy photon index beta = -3.0( < -2.3),
the peak energy Ep = 245(-40, +45) keV (chi2 = 51/60 dof).

Due to uncertainties in the burst incident angle
the quoted values are preliminary.
All the quoted errors are at the 90% confidence level.
--