Illustration of the selection of cluster member stars for NGC 2210. (a) The m_F814W vs m_F606W – m_F814W CMD of well-measured stars in the field of the cluster for which PMs have been determined (b) 1D relative PMs as a function of the m_F814W magnitude. The blue line (drawn by hand) follows our selection of likely cluster members (black dots) based on their motions. (c) CMD of PM-selected cluster members. (d) CMD of PM-selected cluster stars, including only stars within one effective radius from the cluster centre.