Radial velocity-corrected trailed spectrum (top) and the combined absorption line (bottom) resulting from the least square deconvolution for the data before the zenith break. Dark and light grey regions on the average line profile at the bottom panel show the 1-σ and 2-σ of the standard deviation throughout the orbit, respectively. Solid vertical lines depict the maximum allowed radius for the secondary star (i.e., its Roche-lobe radius R_L1). The vertical dashed lines mark the estimated radius R_MS (central lines) and the corresponding 1-σ confidence levels obtained from the RT by the χ² landscape technique.