fitting the X-ray light curve with a simple model based on the intrinsic X-ray emission alone cannot teach us much about the orientation. Almost any inclination and periastron orientation can be fitted with some adjustment of the poorly known binary and wind parameters.

THE COLUMN DENSITY {#sec:N_H}
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In this section we discuss the hydrogen column density as deduced from X-ray observations by H07. This section is based on the calculations of KS08, but significant improvements are added.

We start by describing the observations which we are later rely upon. The column density toward the hot gas was deduced by H07 using their XMM-Newton observations. The binary system itself and its close surroundings are not resolved, but they are distinguished from the extended X-ray emission in the XMM-Newton observations. The XMM-Newton observations cover a very small fraction of the orbit. The RXTE observations, on the other hand cover more than 2 orbits (Corcoran 2005), but do not have the spatial resolution to separate the central source from the extended source. In any case, most of the X-ray emission during most of the orbit result from the binary system.

We shall focus our discussion on the hot $>5 \keV$ component. At 