Non-inertial co-orbital system defined by the radial r̆, transversal t̆, and normal direction n̆ to the SBO. The symbol ⊙ marks the Sun's position on its orbit, B is the barycentre. The solar movement is anti-clockwise, prograde, regarding B. L is the Sun's orbital angular momentum, is parallel to n̆. The vector a_r is the Sun's acceleration decomposed in the radial direction (a_r < 0).