Upper and middle panels: position of IP (blue dotes) and IR (red dotes) RGB stars in the fields of the three GCs. Lower panels: cumulative RDs for IP (blue continuous line) and IR (red dashed line) RGs. PRAD from the cluster centers, (R), and the rectangular coordinates X and Y (whose axes are aligned along the α and δ axes, respectively) with respect to the centers of the clusters are expressed in arcseconds.