CMD of all the remaining sources after the removal of the foreground (black) and only those sources belonging to the medium and coarse grid regions (red) in Fig. 15. The horizontal line represents the position of the TRGB at K₀ = 17.41 mag. The vertical lines represent the colour selection criteria at (J − K)₀ = 0.74 and 1.20 mag. The diagonal lines at J₀ = 18.61 and 18.0 mag represent alternative selection criteria (see Sect. 5.3.3).