Top panel: JH vs. HK diagram for our L1641 targets. Dwarf MS and classical T Tauri loci (Meyer et al. 1997) are indicated by a continuous black line and a dashed magenta line, respectively. Black dotted dashed lines show the reddening vectors. Bottom panel: IRAC colour − colour diagram for the L1641 targets. The black dotted dashed rectangle delineates the domain of Class II YSOs (Allen et al. 2004), two parallel lines indicate the locus of reddened Class II sources (Megeath et al. 2004), and an average reddening vector for A_V = 30 mag is plotted, as well.