ψ Per: azimuthally averaged visibility data of Dougherty & Taylor (1992, black points with error bars) and a Gaussian fit to them (thick black line, FWHM of 74 mas corresponding to 518 R_e) over-plotted with the visibility curves derived from our azimuthally averaged models with several different disk sizes indicated in the legend. The dotted line shows the visibility curve of a point source (visibility equal to unity with increasing baseline length).