Spatial distribution of the final red giants sample. Left: distribution in the Galactic longitude (ℓ) and latitude (b) plane. The colour bar shows the number density of stars per pixel. Each pixel has a size of 1 degree in both latitude and longitude. Right: same but projected into the Galactic plane. Each pixel has a size of 0.05 kpc and 0.06 kpc in the x and y coordinates, respectively. In this figure, the Galactic centre is located at (0, 0), the Sun is located at ( − 8.277, 0) and the rotation of the Galaxy is clockwise. We added dashed, black circles at 5 kpc, R₀ = 8.277 kpc, 12 kpc and 14 kpc to ease visualisation. For the transformation to Galactocentric coordinades, we adopt R₀ = 8.277 kpc, z₀ = 25 pc and v_⊙ = (11.1, 251.5, 8.59) km s⁻¹.