Sky science
Light-Time Correction
Direct answer
Light-Time Correction accounts for the finite interval required for light to travel between an event, observer, and reference point.
It aligns an observed signal with its emission geometry.
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At a glance
- Found in
- Astronomy & Skywatching
- Related
- Proper Motion, Radial Velocity, Orbital Elements, Semimajor Axis
It aligns an observed signal with its emission geometry.
A scientific orientation to scale, light, or motion; the article supplies the precise definition.
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The story behind Light-Time Correction
Increasing timing precision made finite light travel an operational correction rather than a curiosity.
A one-minute story
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Why Light-Time Correction matters
Light-Time Correction is essential when positions or periodic events require precise timing.
How to read Light-Time Correction
the appropriate geometric, heliocentric, or barycentric correction speaks to the task.
Light-Time Correction in practice: an example
A planetary observation records where the planet was when its light departed, not at reception.
Where readings of Light-Time Correction go wrong
A common error is to apply one correction indiscriminately to every reference frame.
Sources and editorial method
Research references used for this entry include:
- U.S. Naval Observatory: Astronomical Almanac Glossary - Definitions for astronomical coordinates, time, reference systems, and observable phenomena.
- International Astronomical Union: Standards of Fundamental Astronomy - IAU-maintained standards and algorithms for astronomical reference systems and coordinate transformations.
- Source
- The Great Almanac Dictionary
- Category
- Astronomy & Skywatching
- Last updated
- 2026-09-26
Account for light’s travel time
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Common questions
What is Light-Time Correction?
Light-Time Correction accounts for the finite interval required for light to travel between an event, observer, and reference point.
What do people get wrong about Light-Time Correction?
A common error is to apply one correction indiscriminately to every reference frame.
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