Angular diameter curves as derived from SBCRs. Top: angular diameter of η Aql as a function of the pulsation phase for different SBCRs (from Fig. 6) combined with the V and K light curves (Fig. 5). The gray band corresponds to the uncertainty on the angular diameters caused by the uncertainty of the coefficients of the K04 SBCR. For comparison, we also plot the limb-darkened angular diameter as obtained by VINCI, PTI, and FLUOR measurements. Bottow: V − K color of η Aql.