Left panel: colour–magnitude diagram for all stars from UKIDSS/GPS sky survey (see Sect. 2.4) in the 3′ × 3′ vicinity around Swift J1816.7–1613. Red clump giants are marked by the red circle. Right panel: distance-absorption diagram that demonstrates which types of stars can be appropriate as counterparts for Swift J1816.7–1613 (white areas). The stars (cyan crosses for Be stars and black crosses for other stars) located in the grey areas of the diagram cannot be counterparts (see text for details). The black dashed lines represent the absorption and distance to the Galactic bulge.