Best-fitting Newtonian orbital solution for the binary HD 4552,BD+120090. Top left: the angle φ as a function of inclination. The red circle shows the selected value. Top right: the angle φ - φ₀ as a function of eccentricity. The red circle shows the selected value. Bottom left: the black crosses show ${\chi }_R^2+{\chi }_{{\mathrm{\Gamma }}_{2\mathrm{D}}}^2$ as a function of v_rad/v = sin ψ sin i. The red cross shows the observed value of V_rad/V_tot and its error (see Table B.4). Bottom right: the black crosses show ${\chi }_R^2+{\chi }_{{\mathrm{\Gamma }}_{2\mathrm{D}}}^2$ as a function of γ_2D. The red cross shows the value of Γ_2D and its error (see Table B.4).