a region extending to $\sim 500 \AU$ behind he secondary star that is cleaned from the primary wind by the tenuous secondary wind. Namely, when observed through the secondary wind region the column density of the primary wind is very low, practically negligible. In the case of $\omega\simeq 270 ^\circ$ (which we oppose), one would indeed observe through the secondary wind, because $90^\circ -i < \phi_a$.

To show this point, we have repeated our calculation for an opposite periastron longitude $\omega=270^\circ$. The results are shown in Fig. \[fig:NH270\]. We see that for that case the column density long before and after periastron is highly underestimated. Moreover, close to periastron the calculated hydrogen column density reaches $\sim 3\times 10^{24}\cm^{-2}$ (outside the plotted region of Fig. \[fig:NH270\]). This is about 5 times the observed value, while our orientation yields values less than twice the observed value. Even though we admit our calculation of $N_H$ is not applicable during the X-ray minimum, we crudely do get the increase factor of the column density between apastron and periastron as observed by H07. In the case of $\omega=270^\circ$, our calculations show a huge jump in the column density, not compatible with observations. This is mostly 