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.

$$ u = \nu + \omega $$

where $$ u $$ is the argument of latitude, $$ \nu $$ the true anomaly, and $$ \omega $$ the argument of periapsis.