Cross-correlation results for KELT-9b (top panels) and KELT-20b (bottom panels) using all Fe II lines. Left column: cross-correlation residual maps, where the lbright tilted signal is the RM effect, the dark signal is the Fe II atmospheric signal, the red horizontal dashed lines indicate the T1 and T4, and the dashed tilted line represents the expected velocity of the planet where for visualization reasons we assumed v_sys equal to the average v_sys from the single line analysis. Center-left column: same as the maps in the first column, but after correcting for the RM effect. Center-right column: K_p maps in the range of K_p from 0 to 300 km s⁻¹, where the two horizontal gray dashed lines indicate the theoretical K_p and the best K_p values, respectively, and the vertical gray dashed line indicates the mean v_sys value from the single line analysis. Right column: S/N for the best K_p value (black line), fitted Gaussian function (red dashed line), S/N obtained using only the lines detected in the single-line analysis (green line), and S/N obtained using only the lines not detected in the single-line analysis (blue line). The black dashed vertical line indicates the mean v_sys value and the red vertical line indicates the velocity of the signal from the Gaussian fit.