Comparison of the 3D pressure model (green line) and the corresponding projected y profile, smoothed with the 10′ beam. The dotted black line shows the expected y profile due to the inner power component, while the dashed line shows the contribution of the outer power law component. The black solid line is the sum of these two components. For comparison, the blue line shows the same model, but not convolved with the 10′ beam. In this plot r_J ~ 30′. Due to projection effects, the range of radii affected by the value of r_J is of order r_J itself. Since r_J exceeds 10′, many independent data points with large signal-to-noise ratio contributes to the determination of r_J, allowing r_J to be estimated with an uncertainty below the nominal angular resolution of the telescope.