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Suzaku observation of IGR J17497-2821

ATel #914; T. Itoh, M. Kokubun, T. Yuasa, S. Yamada, K. Makishima (Univ. Tokyo), A. Kubota (RIKEN/Japan), H. Takahashi (Hiroshima Univ.), R. Walter (ISDC/Switzerland), T. Takahashi, T. Dotani, K. Ebisawa, S. Naik, T. Anada (ISAS/JAXA), R. Smith (GSFC/NASA), Y. Ueda (Kyoto Univ.), and the Suzaku team
on 11 Oct 2006; 16:20 UT
Credential Certification: Motohide Kokubun (kokubun@phys.s.u-tokyo.ac.jp)

Subjects: X-ray, Gamma Ray, Black Hole, Transient

From 2006 Sept 25 7:00 UT through Sept 26 14:14, Suzaku performed a TOO observation of the hard X-ray transient, IGR J17497-2821, which was recently discovered by INTEGRAL (Soldi et al., ATEL #885). A net exposure of ~50 ksec was achieved. As the source is very bright both in the soft X-ray and hard X-ray range, Suzaku has detected its signals from ~0.5 keV up to almost ~300 keV. Preliminary analysis shows that the 1 - 70 keV wide-band spectrum can be approximated by a single power-law with a photon index of 1.6 +/- 0.1, absorbed by N_H = (4.6 +/- 0.3) x 10^22 cm^-2. Above ~100 keV, the spectrum shows evidence of gradual cutoff. The spectrum also has a hint of structures in the 5-8 keV band, which is consistent with the iron K absorption edge. The source flux is estimated to be ~5.0 x 10^-10 ergs s^-1 cm^-2 in the 2 - 10 keV band, and ~4.2 x 10^-10 ergs s^-1 cm^-2 in the 12 - 40 keV band. Assuming a distance of 8 kpc, these correspond to the source luminosity of 3.8 x 10^36 ergs s^-1 (2 - 10 keV) and 3.2 x 10^36 ergs s^-1 (12 - 40 keV). The source flux below 10 keV showed a decline by 5 - 10 percent during the observation, together with slight variations in the spectral hardness.