Proper motions of the target RGB stars from the Gaia EDR3 catalogue (Gaia Collaboration 2021). Identifications of non-member stars are shown next to the symbols. The region that encloses motions falling within 1.5 mas yr^-1 from the mean cluster proper motion is marked by a orange circle. Stars falling outside this region were rejected from the abundance analysis. Zoomed-in region marked by a square is shown in the top right corner.