Upper panel: proper motion diagram of UMi’s Gold RR Lyrae stars (black filled circles) and 43 variable stars significantly brighter than UMi’s HB, that are placed within (magenta filled circles) and beyond (yellow filled circles) 12 r_h from the centre of the galaxy. Lower panel: zoomed-in view of the upper panel. The labelled sources are discussed in Section 4. The green filled circles mark V56 and V80, for which we do not confirm N88’s classification as ACs.