Rotation curve of NGC 4523 measured from the high-resolution H I velocity field within the modelling approach described in Sect. 5.2. Blue and red squares show the approaching and receding sides of the rotation curve, respectively. The green solid line indicates the best-fitting analytic rotation curve (solid body in the inner regions, and flat in the outer parts). Left panel: rotation curve derived leaving all the fitting parameters free. Right panel: rotation curve derived by shifting the position of the kinematic centre by 4.4″ compared to that in the left panel in order to minimise the difference between the approaching and receding side in the inner regions.