V1180 Cas near-IR two-colour plot. Points with J< 13.50 mag and J> 15.5 mag are marked in blue and red, respectively. Circles refer to our data, triangles show results form 2MASS (Skrutskie et al. 2006) and K11. The solid line shows colours of main-sequence stars, the dashed line the locus of T Tauri stars (Meyer et al. 1997). The dotted lines indicate the extinction vectors from Rieke & Lebofsky (1985; black) and Cardelli et al. (1989; red), with squares marking the positions corresponding to A_V = 0, 1, 5, 10, 15, and 20 mag.