Top panel: sketch of the system with the stream trailing the neutron star as it orbits HD 77581; the solid line indicates the wind density distribution along the line of sight (indicated with an arrow). Bottom panel: orbital absorption curve as observed with MAXI (crosses, uncertainties at 1σ confidence level), and model curves calculated for the smooth-wind model (dashed line, see also Fig. 2), and for a model with stream trailing the neutron star (solid line). We arbitrary shifted the curve for the smooth model to enhance the plot clarity.