Argument of latitude

In celestial mechanics, the argument of latitude ( u ) is an angular parameter that defines the position of a body moving along a Kepler orbit. It is the angle between the ascending node and the body.

It is the sum of the more commonly used true anomaly and argument of periapsis.

u = ν + ω

where u is the argument of latitude, ν the true anomaly, and ω the argument of periapsis.