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ATEL # 1038; K. Yamaoka (Aoyama Gakuin University), T. Dotani (ISAS/JAXA) and J. H. Swank (NASA/GSFC)
on 31 Mar 2007; 18:42 UT
Password Certification: Kazutaka Yamaoka (email@example.com)
Subjects: X-ray, Binaries, Black Holes, Transients
We performed two RXTE pointing observations of the black hole binary candidate XTE J1856+053 (ATels #1024,#1026), on March 9 and 24.
Energy spectra of both sets of observations are quite similar. The PCA spectra are well fit with a multi-color disk (MCD) model with Tin = 0.72+-0.02 keV plus a power-law with a photon index gamma = 2.0+-0.5, modified with Galactic absorption (fixed at the Galactic value NH = 3.3e22 cm^-2). The fluxes in the 2-10 keV range were 1.3e-9 erg/cm^2/s, corresponding to about 56 mCrab, for both observations. These results are typical of black hole sources in a high/soft state. They also indicate that the XTE J1856+053 stayed at an approximately constant flux level for a few weeks after its rise on March 5 (ATel #1024).