Latitude Argument

in astronomy, a value that determines the position of a celestial body (a planet, satellite, and such) in its orbit; it is the angle between the nodal line and the radius-vector of the celestial body (see Figure 1). It is calculated from the ascension node of the orbit in the body’s direction of motion.

Figure 1. Perigee (perihelion) and latitude arguments: Ω℧ —nodal line; II-perigee (perihelion); S-celestial body; Ω-perigee (perihelion) argument; ΩS—latitude argument.