Upper panels: Orbit of BPM 3066 in the plane of the Galaxy (Y vs. X, right panel) and in the meridional plane (Z vs. $R=\sqrt{X^2+Y^2}$, left panel). Galactocentric cartesian coordinates are designated by X, Y, and Z, Z being the height over the Galactic plane. The circle with a dot symbol (⊙) in both panels shows the position of the Sun today, while the filled black star is the current position of BPM 3066. Bottom panels: Orbital energy, E, vs. the vertical component of the angular momentum, L_Z (left panel) and the action diamond (right panel, see text for details). BPM 3066 is marked with the black filled stars. The background population is the ‘good-parallax sample’ of Bonifacio et al. (2021), with stars classified as thin, thick, and halo stars shown as red, green, and grey dots. Gaia-Sausage-Enceladus and Sequoia/Thamnos candidates are shown in magenta and cyan, respectively. The shaded cyan region in the action diamond shows the criteria adopted from Feuillet et al. (2021) to select Sequoia candidates.