Combined cross-correlation function (CCF) calculated at pairs of K_p and velocity for Na (top left), Hα (top right), K D₁ (bottom left), and Na+Hα+K D₁ combined (bottom right). The CCF has been normalized and expressed in the form of S/N. The plus sign marks the maximum S/N location. The dotted lines refer to K_p = 167 km s⁻¹ and zero velocity. The sub-panel above the K_p map shows the normalized CCF at K_p = 167 km s⁻¹.