Comparison of FWHM (m s⁻¹) for ¹²CO ALMA data (blue line) and the RADMC-3D optically thin model (dashed red line), where the FWHM is derived by fitting a Gaussian to each spectrum (assuming azimuthal sections of 15° for the data) using an MCMC approach for both the model and data. For both the model and the data, an annulus between $0_{\cdot }^{\mathrm{\prime }\mathrm{\prime }}61$ and $0_{\cdot }^{\mathrm{\prime }\mathrm{\prime }}63$ (corresponding to the disc’s peak radial surface density) is extracted. The error bars for the ¹²CO ALMA data (shaded regions) have been re-scaled by a constant factor, which was fitted for.