[LEAPSECS] [time-nuts] Leap Quirks

[Tony Finch]

On Mon, 5 Jan 2009, Rob Seaman wrote:

>

> Stabilizing civil time with respect to the slowly evolving diurnal rate is

> important.  You say so yourself:

>

> 	http://catless.ncl.ac.uk/Risks/25.50.html#subj1


That post is not entirely serious :-) Perhaps I should post a followup
without my tongue in my cheek that explains the RISKS that the sunrise
time idea is supposed to make readers think about.


> The ITU proposal to simply ignore the whole thing for a thousand years

> is not one of these.


I should probably be clear that I use the term "civil time" to mean what
wall clocks say. You seem to use it to mean UT.

My opinion is that the time zone system is enough to cope with the offset
between civil time and atomic time (whether that's TAI or GPS or TI or UTC
without leap seconds). The TZ mechanism has a theoretical resolution of a
minute, but in common use we usually round offsets to the hour (apart from
a few brave jurisdictions). It has a theoretical range of over four days
which should suffice considerably further into the future than the current
UTC rules. It has a well-exercised mechanism for revising offsets that is
devolved, rather than requiring global consensus. I don't see why we need
more than one mechanism for resetting our clocks to match the hours of
sunlight.

The above is basically what I said in my RISKS item, except with the
absurd parts removed. Sunrise time's fine-grained DST adjustments are
crazy because they optimise for precision at the expense of ease of use.
Sounds like UTC's leap seconds...

Tony.
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