Circular velocity curves derived using all the spaxels with measured velocities (panel a). The circular velocity curve based on the H_α velocities is shown by the open circles (case A_R, the radial motion is neglected) and by the solid line (case A_R + E, the radial motion is included). The circular velocity curve based on the H_β velocities is denoted by the plus symbols (case B_R, without the radial motion) and by the dotted line (case B_R + E, with the radial motion). The circular velocity curve based on the stellar velocities is presented by the crosses (case S_R, without the radial motion) and by the dashed line (case S_R + E, with the radial motion). Panel b: radial velocity as a function of radius for the cases A_R + E (open circles), B_R + E (plus signs), and S_R + E (crosses). The geometric parameters and other characteristics of each case are reported in Table 1.