[time-nuts] Re: UTC

Mike S mikes at flatsurface.com
Thu Jul 28 19:42:33 EDT 2005

At 07:28 PM 7/28/2005, Tom Van Baak wrote...
>or leap hours, is suitable to civil time. The key
>thing about UTC is the C, the coordination
>between atomic and astronomical time. The
>UTC leap hour proposal honors that.

The key to your claim, "coordinated," does not refer to the synchronization of UTC with UT1. It refers to coordination of multiple physical clocks. As David W. Allan states: "Time and frequency coordination is the process of combining primary standards to generate coordinated T/F standards for the world or for a particular country." - http://tf.nist.gov/timefreq/general/pdf/619.pdf Here's another NBS document specifically addressing the coordination of UTC, not with UT1, but between clocks: http://tf.nist.gov/timefreq/general/pdf/1744.pdf

The "UT" in UTC is of course in reference to Universal Time, and it's variants, all directly linked to earth rotational time. UTC was specifically created to  offer a close approximation of UT1, with the precision of coordinated time (TAI). 

Removing leap seconds makes it indistinguishable from TAI with the exception of a fixed offset, and the ability of lazy sysadmins to claim they're keeping time correctly. Such a time scale can not correctly be called "UT," as it would no longer a variant of Universal Time.

The promise of a "leap hour" millennia in the future is disingenuous lip service. If that time should come, there will once again be ineffectual sysadmins complaining that it's too hard and too expensive.

More information about the time-nuts mailing list