Left panel: radial mapping from 0.2–0.6 arcsec of the PI image of J1604 at R′ band. The colour scale is linear and arbitrary. Right panel: azimuthal profile calculated from the mean values obtained between [ 0.35−0.48 ] arcsec (dashed lines in the left panel and in the left panel of Fig. 1). The error bars are from the standard deviation of the data. The solid line represents the best fit of a Gaussian by χ² minimisation. The vertical lines show the location of the minimum of the dip from our observations and from HiCIAO observations (Mayama et al. 2012).