Left panel: zoom of the HB region in the G vs G_BP –G_RP CMD of M3. RR Lyrae stars are plotted as filled squares and with different colours according to their position with respect to the cluster centre. The same colour-coding is adopted as in the left panelof Fig.18, and black filled squares show the variables beyond three times r_h. Right panel: same as in the left panel, but for the G_BP vs. G_BP–G_RP CMD.