Y. E. Nakagawa, T. Tamagawa (RIKEN), K. Yamaoka, S. Sugita, A. Yoshida
(Aoyama Gakuin University), R. Sato, M. Ohno (ISAS/JAXA), K. Nakazawa
(University of Tokyo), M. Tashiro, T. Sugasahara, W. Iwakiri, K. Onda
(Saitama University), Y. Urata (National Central University), D. Yonetoku,
T. Murakami (Kanazawa University), N. Kawai, R. Usui, H. Nakajima, A. Endo
(Tokyo Institute of Technology), M. Yamauchi, E. Sonoda, N. Ohmori,
K. Kohno, H. Hayashi, A. Daikyuji, K. Noda, Y. Nishioka (University of Miyazaki),
M. Suzuki (TKSC/JAXA), F. Tazaki, S. Eguchi, K. Kubota, Y. Ishino, K. Hiroi,
Y. Ueda (Kyoto University), on behalf of the Suzaku GRB ToO team, report:
We report on a Suzaku ToO observation of the GRB 090709A X-ray afterglow
(Morris et al. 2009, GCN 9625), started on 2009-07-09 13:16:17 UT,
for a net exposure time of about 62 ksec (Mitsuda et al. 2009, GCN 9632).
The observation covers time ranging from 23 ksec to 135 ksec after the
Swift/BAT trigger time (2009-07-09 07:38:34 UT). The X-ray afterglow was
clearly detected in the XIS CCDs at a position consistent with that of
the Swift/XRT observations (Morris et al. 2009, 9625). The 0.2-12 keV
light curve is well fit by a power law with a decay index of 1.53+/-0.02.
A preliminary analysis of the XIS data shows that a time average spectrum
in 0.2-12 keV band is well fit by a power law with a photon index of
2.02+/-0.03, absorbed by a hydrogen column density of (2.2+/-0.2)*10^21 cm^-2.
The unabsorbed 0.2-12 keV flux is (5.2+/-0.2)*10^-12 ergs cm^-2 s^-1.
The XIS data confirm the hydrogen column density in excess of the
Galactic value of 6.6*10^20 cm^-2, consistent with the Swift/XRT result
(Rowlinson et al. 2009, GCN 9642).
We would like to thank the Suzaku managers and the operation team
for approving and carrying out the ToO observation.