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TITLE:   GCN CIRCULAR
NUMBER:  9103
SUBJECT: Konus-Wind and Konus-RF observations of GRB 090406
DATE:    09/04/07 16:37:56 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks,
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 bright GRB 090406  triggered Konus-Wind
at T0=62531.417 s UT (17:22:11.417),
and Konus-RF instrument onboard CORONAS-PHOTON s/c
at T0=62535.495 s UT (17:22:15.495).

The burst light curve shows a smooth single-peaked structure
with a duration of ~12 s.

--
As observed by Konus-Wind the source of the burst
is in the south ecliptic hemisphere
at ecliptic latitude of -46.5 +/- 3 degrees.
The burst had a fluence of 6.6(-0.26, +0.17)x10-5 erg/cm2,
and a 0.256-ms peak flux measured from T0+1.536 s
of 2.1(-0.15, +0.14)x10-5 erg/cm2/s
(both in the 20 keV - 2 MeV energy range).

The time-integrated spectrum of the burst
(from T0 to T0+15.616 s) is well fitted
(in the 20 keV - 2 MeV range) by GRB (Band) model
for which:
the low-energy photon index alpha = -1.04 +/- 0.05,
the high energy photon index beta = -2.69(-0.29, +0.19),
the peak energy Ep = 241(-15, +16) keV (chi2 = 53.4/58 dof).

--
As observed by Konus-RF the burst
had a fluence of 7.3(-0.23, +0.11)x10-5 erg/cm2,
and a 0.300-ms peak flux measured from T0+0.600 s
of 2.2(-0.16, +0.14)x10-5 erg/cm2/s
(both in the 20 keV - 2 MeV energy range).

The time-integrated spectrum of the burst
(from T0-0.800 to T0+10.500 s) is well fitted
(in the 20 keV - 2 MeV range) by GRB (Band) model
for which:
the low-energy photon index alpha = -0.86 +/- 0.03,
the high energy photon index beta = -2.54(-0.13, +0.10),
the peak energy Ep = 228(-10, +11) keV (chi2 = 153/133 dof).

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

The Konus-Wind light curve of this GRB is available
at http://www.ioffe.ru/LEA/GRBs/GRB090406_T62531/

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TITLE:   GCN CIRCULAR
NUMBER:  9116
SUBJECT: GRB 090406: pseudo-z= 0.91 from prompt emission spectrum
DATE:    09/04/09 09:43:25 GMT
FROM:    Alexandre Pelangeon at LATT,CNRS,U. Toulouse  <alexandre.pelangeon@gmail.com>

A. Pelangeon & J-L. Atteia (LATT-OMP) report:

We used the spectral parameters of GRB 090406
provided by Golenetskii et al. (GCNC 9103)
to compute the spectral pseudo-redshift(**) of this burst
detected by Konus-Wind and Konus-RF instrument.


We find a pseudo-redshift pz= 0.91 +/- 0.10


** cf. http://www.ast.obs-mip.fr/grb/pz