GRB 090401A
GCN Circular 9071
Subject
Konus-Wind observation of GRB 090401A
Date
2009-04-01T15:45:45Z (16 years ago)
From
Valentin Pal'shin at Ioffe Inst <val@mail.ioffe.ru>
S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, P.
Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind
team, report:
The most intense part of the long GRB 090401A (Swift-BAT trigger
#348128: Schady et al., GCN 9062; Sato et al., GCN 9064) triggered
Konus-Wind at T0=170.845 s UT (00:02:50.845).
The burst light curve shows a weak emission starting at ~T0-120s
followed by the main multipeaked part at ~T0-24s, which had a duration
of ~40s. There is a hint of an earlier emission.
As observed by Konus-Wind the burst
had a fluence of 2.14(-0.17, +0.19)x10^-5 erg/cm2,
and a 256-ms peak flux measured from T0+7.648 s
of 2.79(-0.42, +0.44)x10^-6 erg/cm2/s
(both in the 20 keV - 1 MeV energy range).
The spectrum of the most intense part
(from T0 to T0+16.640 s) can be fitted (in the 20 keV - 1 MeV
range) by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -1.26(-0.14, +0.15),
and Ep = 218(-34, +51) keV (chi2 = 87.9/60 dof).
Fitting by GRB (Band) model yields the same alpha and Ep,
and only an upper limit on the high energy
photon index: beta < -2.3 (chi2 = 87.9/59 dof).
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/GRB090401_T00170/
GCN Circular 9085
Subject
GRB 090401A: Suzaku WAM observation of the prompt emission
Date
2009-04-04T08:27:36Z (16 years ago)
From
Kazutaka Yamaoka at Aoyama Gakuin U <yamaoka@phys.aoyama.ac.jp>
M. Suzuki, M. Ohno, M. Kokubun, T. Takahashi (ISAS/JAXA),
N. Kodaka, W. Iwakiri, M. Tashiro, Y. Terada, Y. Urata, A. Endo,
K. Onda, K. Morigami, T. Sugasahara (Saitama U.), T. Enoto,
K. Nakazawa, K. Makishima (Univ. of Tokyo), S. Sugita, K. Yamaoka
(Aoyama Gakuin U.), Y. E. Nakagawa, T. Tamagawa (RIKEN), T. Uehara,
T. Takahashi, Y. Fukazawa, C. Kira, Y. Hanabata (Hiroshima U.),
E. Sonoda, M. Yamauchi, H. Tanaka, R. Hara, N. Ohmori, K. Kono,
H. Hayashi (Univ. of Miyazaki), S. Hong (Nihon U.), N. Vasquez
(Tokyo Tech.), on behalf of the Suzaku WAM team, report:
The bright long GRB090401A (Swift/BAT trigger #348128; Schady et al.,
GCN 9062; Sato et al., GCN 9064) was detected by the the Suzaku Wide-band
All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV
at 00:02:34.509 UT (=T0).
The observed light curve shows a multi-peaked structure lasting from
T0-5s to T0+38s. There is also a weak precursor starting at ~T0-103s,
resulting in the total duration (T90) of about 112 seconds.
The fluence in 100 - 1000 keV was 1.37(-0.10,+0.08) x10^-5 erg/cm^2.
The 1-s peak flux measured from T0+27s was 5.1(-0.4,+0.5) photons/cm^2/s
in the same energy range.
Preliminary result shows that the time-averaged spectrum from T0-5s to
T0+38s is fitted by a single power-law with a photon index
of 2.14 (-0.13,+0.14) (chi^2/d.o.f = 21.4/24).
3 % systematic errors were included in low energy channels.
All the quoted errors are at 90% confidence level.
The light curves with 1-sec time resolution for this burst will be appeared at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/untrig/grb_table.html