Distribution of the observed sample on the plane of the sky of NGC 5139, with x = (RA₀ − RA) ⋅ cos(Dec) and y = Dec − Dec₀ (RA₀ and Dec₀ being the coordinates of the cluster center, adopted from Vasiliev & Baumgardt 2021 catalog). The colors distinguish stars with radial velocities referred to the cluster systemic velocity (${\stackrel{\sim }{V}}_r)>0$ (in red), from those with ${\stackrel{\sim }{V}}_r<0$ (in blue). Black arrow vectors indicate the north (N) and east (E) direction.