Column mass densities and the corresponding rotation curves of finite-width disks with a Mexican hat vertical profile (h = 117 pc), shown at several steps of the iteration method of Sect. 2.1, starting from the surface density of an infinitesimally thin disk. Top panel: column mass densities at various iteration steps (thin gray lines), surface mass density of the infinitesimally thin disk model (the starting point of the iteration, triangles), MW column mass density in the final iteration step (it gives the interpolating rotation curve in the bottom panel, solid circles). Bottom panel: (open circles) MW rotation curve points from Sofue et al. (1999), (thin gray lines) rotation curves at various iteration steps, and (thick line) rotation curve in the final iteration step (it strictly overlaps with a spline interpolation of the MW rotation curve points).