Light variations of the C-type Mira RU Vir in the visual (AAVSO data; black dots) and in the K-band (adopted from Whitelock et al. 2006; red points). The arrow marks JD 2 447 336 which was determined to be a maximum phase (φ_v = 0) from the AAVSO data and then adopted to estimate phases for the NIR data (see text). On top of the regular variation some long-term trend can be recognised (cf. Fig. 2b in Mattei 1997).