Dictionary term
DUT1
Direct answer
DUT1 is the published correction UT1 minus UTC used to approximate Earth-rotation time from a UTC signal.
DUT1 is the broadcast difference between UT1 and UTC.
DUT1 is the broadcast difference between UT1 and UTC.
A cycle or timeline schematic for comparing the named timekeeping concept.Quick reference
- Use when
- Use DUT1 with official IERS or national time-service bulletins for calculations requiring subsecond Earth orientation.
- Do not use it for
- Do not reuse an old DUT1 value; it changes as Earth rotation evolves and is regularly updated.
- Reference category
- Calendars & Timekeeping
- Related terms
- Delta T, Earth Rotation Angle, Calendar, Julian Date
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The story behind DUT1
Radio time services began broadcasting DUT1 corrections as atomic UTC and variable Earth rotation were coordinated.
DUT1 in spiritual tradition
Spiritually, DUT1 is a compact example of measurement keeping uniform clocks connected to the moving Earth.
DUT1: 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.
DUT1 in numerology
DUT1 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 DUT1 matters
It lets navigation, astronomy, and surveying users obtain rotational time without receiving a separate full UT1 time service.
DUT1 at work: an example
Adding the signed DUT1 value to UTC gives an approximation of UT1 for the same instant.
Where interpretation stops
DUT1 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:
- IERS Glossary: Universal Time (UT1) - Official definition of UT1 as Earth-rotation time and its publication as UT1-UTC.
- NIST: UTC(NIST) Time Scale - Official description of UTC realization, atomic time, and leap-second coordination.
- Source
- The Great Almanac Dictionary
- Category
- Calendars & Timekeeping
- Also appears in
- Calendars & Timekeeping
- Aliases
- None listed
- Last updated
- 2026-07-16
Retrieve the current DUT1
DUT1 in a book is one thing; DUT1 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
- GPS Time
- ISO Week Date
- Local Sidereal Time
- Proleptic Gregorian Calendar
- Solar Noon
- UTC Offset
- Barycentric Coordinate Time
- Civil Day
Common questions
What is DUT1?
DUT1 is the published correction UT1 minus UTC used to approximate Earth-rotation time from a UTC signal.
How is DUT1 used in an almanac?
Use DUT1 with official IERS or national time-service bulletins for calculations requiring subsecond Earth orientation.
What should I avoid when interpreting DUT1?
Do not reuse an old DUT1 value; it changes as Earth rotation evolves and is regularly updated.
