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We present highlights from a series of four simultaneous Suzaku/RXTE observations of the black hole candidate Cyg X-1. We briefly summarize several key results from our decade long RXTE monitoring campaign. We then comment on challenges of analyzing the Suzaku data, i.e., improving the aspect correction beyond that of the existing tools, and quantitatively assessing pileup. All of our Suzaku observations (one, by design) occurred at or very near orbital phase 0 (superior conjunction), and hence show evolution in color-color diagrams due to X-ray absorption by material from the wind of the secondary. We present simple partial absorption models for this evolution. We then compare the Suzaku and RXTE data, and explicitly divide the Fe line region into narrow and broad components. Both are required for the Suzaku data, and are seen to be consistent with the RXTE data. These Suzaku observations occurred near historically hard, low flux states. We present fits of the broad band spectra with a simple phenomenological broken powerlaw model, as well as a more physically motivated Comptonization model. Whereas the former class of models described nearly all of the RXTE campaign better than any physical model, here the latter model is slightly more successful. The Comptonization model, however, exhibits little evidence for a soft disk component, which formally corresponds to a small, inner disk radius. Whether this is physical, due to unmodeled absorption, or is a calibration issue, remains an open question.
We present the results of the spectroscopic observations of HDE 226868, the optical counterpart to the black hole X-ray binary Cyg X-1, from 2001 to 2006. We analyze the variabilities of the two components in the complex H$alpha$ line: one P-Cygni sh
The geometry of the accretion flow in black-hole X-ray binaries in the hard state, in particular the position of the disc inner edge, has been a subject of intense debate in recent years. We address this issue by performing a spectral study of simult
X-ray shots of Cyg X-1 in different energy bands and spectral states have been studied with PCA/RXTE observations. The detailed shot structure is obtained by superposing many shots with one millisecond time bin through aligning their peaks with an im
The star HDE 226868 known as an optical counterpart of the black hole candidate Cyg X-1 has been observed in H_alpha region using spectrograph at Ondrejov 2-m telescope. The orbital parameters are determined from HeI-line by means of the authors meth
A report is presented on Suzaku observations of the ultra-luminous X-ray source X-1 in the starburst galaxy M82, made three time in 2005 October for an exposure of ~ 30 ks each. The XIS signals from a region of radius 3 around the nucleus defined a 2