Left panel: derived 2D photocentre displacement vectors for the Brγ line + continuum determined from our AMBER MR-K data. The black line shows an estimated PA for the displacement between blue- and red-shifted vectors. Right panel: differential phase (DP) data for MWC 147 observed with AMBER’s MR-K mode(circular points) compared with differential phases calculated from the photocentre shifts shown in the right panel of this figure (black lines). The baseline label in the upper corner gives the PA in degrees and the baseline (BL) in metres. The line (red and blue) and continuum (grey) points from the left panel correspond to the similar coloured points in the right panel.