Taking the Leap: Moving to Continuous UTC
Andy Kopf  1  
1 : United States Naval Observatory

The irregular rotation speed of the Earth causes constant challenges in timekeeping.
The imprecise observe solar time (UT1) routinely drifts away from the precise International
Atomic Time (TAI), the latter of which is the foundation of the widely used international
timekeeping standard Coordinated Universal Time (UTC). As a result, the leap second was
introduced in 1972 to keep the UTC and UT1 systems within 0.9 seconds of each other at
all times. This process has since become a regular occurrence, as it has been applied 27
times in the last 50 years. On November 18, 2022, the General Conference on Weights and
Measures (CGPM) passed a resolution recommending the move to timekeeping on continuous
UTC no later than the year 2035. Once put into effect, UTC and UT1 would diverge, as
UTC would instead mirror Terrestrial Time (TT) by a constant time offset that would
include a large initial offset to help UTC remain continuous for at least a long period.
This change in timekeeping has wide-reaching implications on the astronomical community,
and this presentation will focus on some of the practical effects of this redefinition. This
discussion will include emerging challenges and potential solutions, including those present
in astronomical observation and almanac data.

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