Simulated velocity field corresponding to four different couples of inclination angle β and dynamical mass M_dyn = 5.0 × 10¹⁰/​​sin²β. Increasing the dimension of the beam FWHM (shadowed area), the iso-velocity curves are increasingly smoothed, and different configurations of the disc appear almost indistinguishable. The simulated maps are obtained with the kinematical model for a galaxy thin disc with R_D = 0.125″, γ = −90 deg. The other parameters defining the model are set as equal to the model in Fig. 5.