Differences between rotation curves obtained with the Gaussian and quadratic methods. Left panel: comparison between the rotation curves from the model (black line, Eq. (5) with a disc mass of M_d = 0.1 M_⊙), the Gaussian method (blue line), and the quadratic method (orange line). We observe that the Gaussian curve is systematically shifted with respect to the model. Right panel: difference between the extracted rotation curve (Gaussian method in blue, quadratic method in orange) and the model v_ϕ from Eq. (5).