Old instruments
Transit Instrument
Direct answer
Transit Instrument is a telescope mounted to move chiefly in the meridian plane so crossings can be timed.
Transit Instrument is a meridian timing telescope used in historical astronomy, timekeeping, or navigation.
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At a glance
- Found in
- Historical Almanacs & Instruments
- Related
- Gnomon, Meridian Circle, Mural Quadrant, Zenith Sector
Transit Instrument is a meridian timing telescope used in historical astronomy, timekeeping, or navigation.
An engraved functional orientation; the page explains the real instrument, method, or publication.
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The story behind Transit Instrument
Transit instruments powered observatory time services, longitude work, star catalogues, and geodetic surveys.
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The Book of the Sky
How people learned to read the sky, from Babylon to the day you were born.
Why Transit Instrument matters
Transit Instrument matters because precise transit times connect star coordinates, sidereal time, longitude, and observatory clocks.
Transit Instrument in practice: an example
An observer records when a clock star crosses each reticle wire and averages the times.
Where readings of Transit Instrument go wrong
Collimation, azimuth, level, personal reaction time, and clock error all affect the result.
Sources and editorial method
Research references used for this entry include:
- Royal Museums Greenwich: Astronomical and Navigational Instruments - Museum reference collection for historical observing, calculating, timekeeping, and navigation instruments.
- Royal Museums Greenwich: A Unique History of Timekeeping - Museum overview of marine chronometers, astronomical regulators, and the development of precision timekeeping.
- Source
- The Great Almanac Dictionary
- Category
- Historical Almanacs & Instruments
- Last updated
- 2026-09-26
Explore Transit Instrument
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More in Historical Almanacs & Instruments
- Armillary Sphere
- Calendar Wheel
- Davis Quadrant
- Greenwich Hour Angle
- Longitude by Chronometer
- Moon Sight
- Planet Sight
- Sector Instrument
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Common questions
What is a transit instrument?
Transit Instrument is a telescope mounted to move chiefly in the meridian plane so crossings can be timed.
What do people get wrong about a transit instrument?
Collimation, azimuth, level, personal reaction time, and clock error all affect the result.
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