Illustration of the systematic covariance relative to the statistical covariance. Σ is the variance-covariance matrix of the Voronoi-binned velocity dispersions (with target S/N ≈ 23 Å⁻¹ for each bin), σ_stat, x is the statistical uncertainty in bin number x from our fiducial setup, and diag(σ_stat) is a diagonal matrix. We assume no covariance in the statistical uncertainty from each setup for kinematic measurement. Thus the off-diagonal terms in the variance-covariance matrix purely represent the systematic covariance. Most diagonal terms are < 1 (with a median of 0.47), showing that the systematic variances are subdominant to the statistical variances except for bins 29 and 31. These bins are close to images A and C. Thus, they are largely susceptible to the choice of the quasar template, as seen in Figs. 6 and 7.