Time-resolved colour-colour diagrams of observation 201. Overplotted (black tracks) are the best-fit models obtained assuming $log\xi =log\frac{10+[N_{\mathrm{H},\mathrm{w}}/{10}^{22}{\mathrm{cm}}^{-2}]}{[N_{\mathrm{H},\mathrm{w}}/{10}^{22}{\mathrm{cm}}^{-2}]}+1$. The contour plots represent the 99.7% (in black), 95% (in grey) and 68% (in light grey) confidence levels of the data distribution during the least absorbed stages of the orbit (ϕ_orb = 0.43 − 0.46, see Appendix C).