Individual (thin line) and summed (thick line) normalized spectrum of the periastron night around one of the selected lines (Fe I 5415.1920 Å). Synthetic spectra with T_eff = 8500 K (dotted line) and T_eff = 4750 K (dashed line) were overplotted (log g = 4.0, v_micro = 2 km s^-1 solar abundances for both spectra), showing the location of the individual lines. The secondary’s spectrum was corrected by the local luminosity ratio. Neither fundamental parameters nor local luminosity ratios are perfectly tuned at this stage.