[LEAPSECS] Straw men

[Ian Batten]

On 9 Jan 2012, at 13:24, Rob Seaman wrote:


> I

> Redefining UTC will break things immediately in astronomy and aerospace and related applications.  And it will break things at unpredictable intervals over the decades and centuries to come. 


And you accuse others of erecting straw men?  Are you saying that if UTC were redefined tomorrow, in a hundred years time there would still be equipment in use that would be mis-behaving?  Or that you would continue to design and procure new equipment relying on a timescale that no longer had the properties you require?  Or what?

We get that you say you've got instruments that rely on a steady diet of UTC which either assume that DUT1 is negligible for the purpose at hand (in which case it's not clear why |DUT1|<0.9s is fine while |DUT1|<1.1s is the end of the world), or are designed such that although they can add DUT1 to the received UTC, they can only do that if |DUT1|<0.9s.  In either case, it sounds like your problem is that you need UT1.  

But presumably what you _really_ want is local apparent solar time, or some such, in order to point instruments, in which case you need to combine UT1 with both the equation of time and the longitude of your location.  It really defines belief that in systems which combine UTC, DUT1, EoT and position it will take centuries to add in an additional offset. 

And as no-one else has that requirement, pace all the bizarre claims about bear hunting, car accidents and legislative effectiveness dates --- all of which require civil time, whatever that might be --- and given the maximum error on the relationship between civil time and local apparent solar time is upwards of two hours in most countries (width of zone tone + EoT + DST), it does rather sound like the astronomical community has a set of requirements that no-one else shares.  And that in the end, society at large's response may well be a great big "meh", in that removing leap seconds solves problems for 99% of the population, while the remaining 1% need to just sort out their own house.  Sorry.

ian