Dictionary term
Local Sidereal Time
Direct answer
Local Sidereal Time is sidereal time adjusted for an observer's longitude, indicating the right ascension on the local meridian.
Local Sidereal Time tells which right ascension is crossing a site's meridian.
Local Sidereal Time tells which right ascension is crossing a site's meridian.
A cycle or timeline schematic for comparing the named timekeeping concept.Quick reference
- Use when
- Use Local Sidereal Time for telescope alignment, hour-angle calculation, and planning when an object culminates.
- Do not use it for
- Use the correct longitude sign and distinguish local sidereal time from local civil time.
- Reference category
- Calendars & Timekeeping
- Related terms
- Greenwich Sidereal Time, Dynamical Time, Calendar, Julian Date
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The story behind Local Sidereal Time
Local sidereal clocks were standard observatory instruments before computerized mount control.
Local Sidereal Time in spiritual tradition
Spiritually, local sidereal time can cultivate place-based sky awareness without implying stellar control.
Local Sidereal Time: fact and faith, kept distinct
This is a factual calendar, astronomy, Earth-science, cultural-history, or observational reference. It can support wonder and practical planning without becoming a claim of fate, spiritual causation, or private revelation.
Local Sidereal Time in numerology
Local Sidereal Time is not a numerology claim. Any numbers attached to it should retain their ordinary scientific, calendrical, navigational, or historical meaning unless a separate symbolic interpretation is clearly labeled.
Why Local Sidereal Time matters
It connects a celestial catalog to the sky currently overhead at a particular observing location.
Local Sidereal Time at work: an example
An object culminates near the moment its right ascension equals the observer Local Sidereal Time.
Where interpretation stops
Local Sidereal Time is presented as sourced astronomy, calendrical, Earth-science, cultural, or instrument-history reference. Definitions should distinguish measured phenomena from civil convention and historical interpretation, preserve location and time dependencies, and avoid turning factual sky data into a deterministic personal claim.
Sources and editorial method
Research references used for this entry include:
- U.S. Naval Observatory Circular 179: The IAU Resolutions on Astronomical Reference Systems, Time Scales, and Earth Rotation Models - Technical reference for TAI, TT, TCG, TCB, TDB, UT1, sidereal time, epochs, and Earth rotation.
- IAU SOFA: Time Scale and Calendar Tools - IAU-standard algorithms and guidance for civil calendars, Julian dates, and seven recognized astronomical time scales.
- Source
- The Great Almanac Dictionary
- Category
- Calendars & Timekeeping
- Also appears in
- Calendars & Timekeeping
- Aliases
- None listed
- Last updated
- 2026-07-16
Calculate what crosses your meridian
Local Sidereal Time in a book is one thing; Local Sidereal Time in your own birth chart is your life. The Oracle casts your real chart and tells you what it means for your love, your work, and your year ahead, in conversation, free.
Speak with the OracleRelated terms
More in Calendars & Timekeeping
- Proleptic Gregorian Calendar
- Solar Calendar
- UT1
- Astronomical Year Numbering
- Civil Day
- DUT1
- GPS Time
- ISO Week Date
Common questions
What is Local Sidereal Time?
Local Sidereal Time is sidereal time adjusted for an observer's longitude, indicating the right ascension on the local meridian.
How is Local Sidereal Time used in an almanac?
Use Local Sidereal Time for telescope alignment, hour-angle calculation, and planning when an object culminates.
What should I avoid when interpreting Local Sidereal Time?
Use the correct longitude sign and distinguish local sidereal time from local civil time.
