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Suzaku Observations of XTE J1856+053

ATEL # 1042; E. Cackett, J. Miller (Michigan), T. Dotani (ISAS/JAXA), Y. Fukazawa (Hiroshima Univ.), L. Gallo (St Andrews), A. Kubota (RIKENN/Shibaura Inst. of Tech.), G. Miniutti (Cambridge), S Naik (ISAS/JAXA), S. Nakamura (RIKEN/Tokyo Sci. Univ.), T. Tamagawa (RIKEN/Tokyo Sci. Univ.), Y. Ueda (Kyoto Univ.), K. Yamaoka (Aoyama Gakuin Univ.), and the Suzaku team
on 3 Apr 2007; 14:36 UT
Password Certification: Edward Cackett (

Subjects: X-ray, Binaries, Black Holes, Transients

We report on Suzaku observations of the black-hole transient XTE J1856+053 which recently went into outburst (see ATEL #1024, #1026, #1038).

Suzaku performed a ~25 ks observation of this source starting on March 19th, with the XIS operated in normal mode with a 1/4 window and the aim point at the HXD nominal position.

We fit the extracted spectra from the XIS0, XIS1 and XIS3 simultaneously in XSPEC. The source is well fit by a dominant disk blackbody with a weak power-law tail. From our initial fits, we find, N_H = (3.3 0.1)E22 cm-2, T_in = 0.77 0.01 keV. The power-law is not well constrained in the XIS band. The spectrum is consistent with a high/soft state. We note that the column density we find is consistent with the galactic column towards XTE J1856+053. The 0.5-10 keV source flux is (1.2 +/- 0.2)E-9 ergs cm^-2 s^-1.

There is no clear evidence for any iron emission or absorption features in the spectrum as has been seen in the high/soft state of other black hole transients. Further detailed analysis of this data will be presented in a forthcoming paper.

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R. E. Rutledge , Editor
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