Radio emission contours (shown in black) and Faraday rotation measure of 0552+398, shown in colour. The left panel is with an elliptical beam (shown at bottom left), the middle panel with a circular beam and the Faraday Rotation measure is shown in the right panel. The projected velocity on the plane of the sky is shown with a red arrow at the middle panel and the slice along which the Faraday Rotation is measures is plotted as a black line in the middle panel. Figure reproduced by Gabuzda et al. (2018).