Left: normalized radial cuts of the R′, I′ and J-band images after averaging azimuthally. Right: normalized azimuthal cuts of the R′, I′ and J-band images, after averaging radially between 170 and 200 mas. The radiative transfer model prediction (dotted curve) reproduces the observed azimuthal brightness variations relatively well. Note that due to the large variation of surface brightness along the rim, the standard deviation in each bin can vary from 2 to 17%. The curves are shifted vertically for clarity.