Interferometric radii as function of rotational phase. Uniform and Gaussian disc models are shown with green and yellow markers, respectively. Blue lines correspond to the radii encompassing 50, 80, 90, and 99% of the total RT model’s flux. The blue shaded areas represent the standard deviation of these radii across the rotational phase. The red shaded area indicates the inner (R_t) and outer radius (R_t + δr) of the RT model.