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.

Articles related to orbits

Orbits

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 High Earth Molniya Near-equatorial Orbit of the Moon Polar Tundra Two-line elements

About other points	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 Low energy transfer Oberth effect Inclination change Phasing Rendezvous Transposition, docking, and extraction Collision avoidance (spacecraft)

Other orbital mechanics topics

Apsis Celestial coordinate system Characteristic energy Direct motion Epoch Ephemeris Equatorial coordinate system Ground track Interplanetary Transport Network Kepler's laws of planetary motion Lagrangian point n-body problem Orbit equation Orbital speed Orbital state vectors Perturbation Retrograde motion Specific orbital energy Specific relative angular momentum