Optical counterpart of the X-ray sources in the field of 47 Tuc observed by SkyMapper (Wolf et al. 2018) (left panel) and in the Gaia third data release (Gaia Collaboration 2020) (right panel). The yellow dots are all optical sources detected in the field of 47 Tuc dSph, and the hard grey lines are the theoretical isochrone of the Dartmouth stellar evolution database (Dotter et al. 2008) for the age, metallicity, and distance of 47 Tuc (see Sect. 1). The remaining symbols are the same as in Fig. 2. To show the crowded region of the Skymapper colour-magnitude diagram better, we show a zoom into the dashed square.