Illustration of the methods used to associate the PNFW mass distribution to elliptical contours. In the GK method, a_GK and b_GK correspond to the semi-major and semi-minor axes of the ellipse (dashed line) passing through the intersection of the iso-convergence contour (solid line) with the x₁ and x₂ axes. In the EF method, a_EF and b_EF correspond to the semi-major and semi-minor axes of the best-fitting ellipse (dash-dotted line) obtained by minimizing Eq. (18).