vbroad determination at T_eff = 5500 K, log g = 4.5, [Fe/H] = 0, vbroad = 20 km s⁻¹ (vertical dashed line), and G_RVS = 8. Template mismatch errors are ignored, except for the vbroad broadening, which is the quantity to be derived. Upper panel: top of the CCF centred at 0 km s⁻¹ (grey curves) obtained by assuming various values of vbroad is plotted and shifted according to the adopted vbroad. The peaks are identified by blue circles, and the three-peak and four-peak parabola fits are shown by green and orange curves, respectively. The ordinate axis label ‘CC’ stands for ‘cross-correlation coefficient’. Lower panel: same as in the upper panel, but at different effective temperature values. For clarity, the CCF peaks are connected by a line.