Left: vector point diagrams for all the stars detected in the field, divided in eight one-magnitude bins according to the CMDs on the right. The green circle shows the adopted membership criterion used to selected cluster members in each magnitude interval. We adopted a radius of 4 mas on the brightest bin and allowed a bigger selection region for poorer measured stars (7.5 at the bottom). Middle: clean CMD for the stars assumed to be cluster members (red points inside the green circle in the VPD). Right: CMD for the field counterpart after excluding likely cluster stars.