R Cnc flux, squared visibility amplitude, closure phase, and UD diameter (from top to bottom) as a function of wavelength. Data of the remaining three targets are shown in Fig. 2 of the electronic version. The wavelength range is 1.92–2.47 μm (MR21 mode: 1.92–2.26 μm, MR23 mode: range 2.12–2.47 μm). The modes overlap in the region 2.12–2.26 μm, where the two lines appear as one thicker line. The thick vertical lines denote the errors averaged over three wavelength intervals. The blue lines show a comparison to the best fitting model of the P/M model atmosphere series (Ireland et al. 2004a,b), and the red lines the best fitting model of the new CODEX series (Ireland et al. 2008; 2011). The dashed line shows a uniform disk curve fitted to the 2.25 μm near-continuum bandpass.