Left: reduced χ² map given by the grid disentangling for HD 163892 by combining the He I 4471, Mg II 4481 and Hγ lines. The minimal reduced χ², at K₁ = 41.05 ± 2.50 km s⁻¹, K₂ = 232.5 ± 14.9 km s⁻¹ is shown with a red dot. The solid white lines represent the 1σ contours. The 1D cuts in both directions are given as indications. Right: disentangled spectra of the primary (black) and secondary (green) of HD 163892. The latter has been shifted vertically by −0.25 for clarity.