Left: spatial distribution of Hercules PM-selected stellar sources (black filled circles). Spectroscopic targets are marked as pluses (Deason et al. 2012), squares (Adén et al. 2009a), circles (Simon & Geha 2007) and crosses (Adén et al. 2011). Red (blue) symbols represent spectroscopic targets cross-identified (non-cross-identified) in the PM-selected catalogue. RR Lyrae stars studied by Musella et al. (2012) are marked as green (blue) diamonds. The numbers in parentheses are referred to the numbers of spectroscopic targets and variables cross- identified (non-cross-identified). Sources excluded by the colour–colour selection are shown as grey dots (see Fig. 10). Right: PM- selected r_Sloan vs. B_Bessel − r_Sloan CMD. Symbols are the same as in the left panel. An arrow indicates the binary star Her-3 discovered by Koch et al. (2014).