[LEAPSECS] Leap smear

[Rob Seaman]

On Sep 20, 2011, at 12:09 PM, Ian Batten wrote:


>> Let's see…1 ppm is 0.0864 seconds per day.  That is a leap second (or equivalent drift) every 11.57 days.  A leap hour (presuming such is implementable) every 114 years.  Is this acceptable?  Says who?  What process should be followed? 

> 

> Exactly the same process that the UK followed on the 27th of October 1968.   You wouldn't be leaping UTC, you'd be leaping civil time.  We're used to that.


No, we're used to leaping local civil time.  UTC as international civil time remains an indicator of Earth orientation.  The two are kept separate whatever local authorities choose to do.  However, let's ignore that distinction.


> You just spring forward, but don't fall back.  Need the leap hour in the opposite direction?  Don't spring forward, but leap back, as we did on 31st October 1971.  What's so difficult about it?


If it is not difficult, it should be simple to write up as an addendum to the ITU proposal.  Rather, the ITU is proposing that we just stop issuing leap seconds.  (And dismantle the current procedure for promulgating the resulting offset.)  The proposal is incomplete in both regards.

Or perhaps it is more difficult than that.  System engineering best practices exist to identify and deal with such difficulties.


> So why aren't all those exotic investigations necessary when countries change timezones, which happens with monotonous regularity?


Because the implications are currently local to the particular timezones.


> We've already established that the link between civil time and solar time has an uncertainty measured in multiple minutes, and we've already established that one-hour steps in civil time are trivial to implement, because they happen twice a year.


No.  You have asserted these.  There is a distinction between international civil time and local civil time.

Again - if trivial then it should be simple to write up a white paper describing the plans and providing recommendations that local authorities could use to inform their later policy deliberations.

Rob