Average of squared visibility amplitudes taken in the near-continuum bandpass at 2.15–2.25 μm (one average per baseline and band) for AH Sco (top), UY Sct (middle), and KW Sgr (bottom) as a function of spatial frequency. The red lines indicate the best-fit UD models and the blue lines the best-fit PHOENIX models. The dashed lines are the maximum and minimum visibility curves, from which we estimated the errors of the angular diameters.