Distribution of 3-band Stetson variability index vs. mean H magnitude. Top: 36 365 objects from control sample with 3 band light curve. Higher density of points is shown as darker gray. Bottom: 5083 stars from the candidate member catalog. In both panels, the 3-band light curve is plotted as light gray dots, and darker gray shows regions with high density of points. The dashed red lines show the selection value S = 0.25. In the right plot, periodic stars are plotted in black.