True and model-predicted probability density distributions of stellar orbits in the λ_z–R phase space for different structures in Au-23. The top panels indicate the true distributions while the bottom panels represent the model results from Au-23-85-50. From left to right, the panels show the stellar orbit distributions for the bar, the bulge, the disc, and the stellar halo. The probability densities of all orbits within the data coverage (R ≤ 50 arcsec) are normalised to unity, with their values indicated by the colour bar. The horizontal black dotted lines denote λ_z = 0. The vertical blue dashed lines represent the true and model-predicted bar lengths, R_bar, derived from orbit analysis, with their values shown in the text.