True longitude

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In astrodynamics true longitude is the longitude at which an orbiting body could actually be found if its inclination were zero. Together with the inclination and the ascending node, the true longitude can tell us the precise direction from the central object at which the body would be located at a particular time.

[edit] Calculation

The true longitude $l\,$ can be calculated as follows:

$l=\bar{\omega} + \nu\,$

where:

$\bar{\omega}\,$ is longitude of orbit's periapsis,
$\nu\,$ is orbit's true anomaly.

Orbits

Types

General	Box · Capture · Circular · Elliptical / Highly elliptical · Escape · Graveyard · Hyperbolic trajectory · Inclined / Non-inclined · Osculating · Parabolic trajectory · Parking · Synchronous (semi · sub)

Geocentric	Geosynchronous · Geostationary · Sun-synchronous · Low Earth · Medium Earth · Molniya · Near-equatorial · Orbit of the Moon · Polar · Tundra · Two-line elements

Other	Areosynchronous · Areostationary · Halo · Lissajous · Lunar · Heliocentric · Heliosynchronous

Parameters

Classical	$i\,\!$ Inclination · $\Omega\,\!$ Longitude of the ascending node · $e\,\!$ Eccentricity · $\omega\,\!$ Argument of periapsis · $a\,\!$ Semi-major axis · $M_o\,\!$ Mean anomaly at epoch

Other	$\nu\,\!$ True anomaly · $b\,\!$ Semi-minor axis · $\epsilon\,\!$ Linear eccentricity · $E\,\!$ Eccentric anomaly · $L\,\!$ Mean longitude · $l\,\!$ True longitude · $T\,\!$ Orbital period

Maneuvers

Bi-elliptic transfer · Delta-v budget · Geostationary transfer · Gravity assist · Gravity turn · Hohmann transfer · Oberth effect · Inclination change · Phasing · Rendezvous · Transposition, docking, and extraction