Artificial velocity deviations measured in a perfectly Keplerian disk compared to the observations. Top: differences between the measured ¹³CO J = 3–2 velocity and the Keplerian prescription in a 2D-map (R, θ). Blue and red colors indicate blue- and redshifted velocities along the line-of-sight compared to the Keplerian rotation. Middle: ¹³CO integrated emission. Bottom: flux ratio I_out∕I_in of the emission at the outer and inner edges of the synthesized beam. The left panel is surrounded by a red rectangle because theflux ratio is only an approximation in observations, being measured after beam smoothing. Left column shows the observations. The central and the right columns are the models convolved at a spatial resolution of 0.3 and 0.1′′. The verticalblack bar on the top-left corner of the top panels is the averaged radial spatial resolution as a function of the azimuth.