Empirical VIK instrumental color–color relation. Lower panel: open black symbols show all astrometric matches (that survived a strict crowding criterion) between OGLE-II V/I data and instrumental IRSF K data. The green filled points show those used in the fit (red line), which are restricted to 2.0 < (V − I) < 2.4 and exclude 3σ outliers. Vertical magenta lines show MOA-2007-BLG-192S (V − I) color measurement by Gould et al. (2010). Upper panel shows the VI CMD positions of stars used to determine the VIK relation. They are all giants in or near the clump, whereas the source (magenta point) is a dwarf. Nevertheless, Bessell & Brett (1988) show that the VIK relations are essentially identical for giants and dwarfs in this color range (see text).