Values of O–C from the m₁ SOFIN RV curve of Si III 4552 Å, using the best-fit obtained with FOTEL. From bottom to top, the sets correspond to JD–2 445 543-n, with n = 0,1,2,3, and each set is shifted along the vertical axis by, respectively, c = 0, 10, 20, 35 km s^-1, which is indicated by the horizontal lines. The mean orbital phase is indicated, and the arrows point to the two possible times of conjunction when m₂ is in back of m₁ (see Tables 3 and 4).