K_p-v_sys matrices of S∕N values for the Plez98 model from Nugroho et al. (2017), with the v_sys-axis restricted to values within ±100 km s^-1 for clarity. Each panel corresponds to the matrix for a different SVD iteration (0–5), indicated above each panel. The strongest peak on the full v_sys range is noted above each panel with the corresponding values of K_p and v_sys. Where applicable, this peak is also marked on each matrix with a cyan ring. The dashed cyan box indicates the region where peaks must be found to be considered significant, as described in Sect. 4. The colorbar binning is based on the local S∕N minimum and maximum on this restricted v_sys range.