[LEAPSECS] When will UT1 definition require replacement?

[Steve Allen]

On Thu 2014-03-20T15:20:43 -0400, Gerard Ashton hath writ:

> There has much discussion on the list about when the current definition of

> UTC will become unworkable, and when a UTC would become unworkable if leap

> seconds are discontinued, but I don't think there has been anything more

> than hand waving about when UT1 would need to change.


That there would be a deviation between mean midnight at Greenwich and
Universal Time was pointed out at least as early as the Explanatory
Supplement from the 1960s.  In the past couple of years Seidelmann and
Seago have looked at the deviation in more detail in

http://www.agi.com/resources/user-resources/downloads/white-paper.aspx?id=162

and there is another nice plot in the final talk and paper at the 2013
Future of UTC meeting in Charlottesville
http://futureofutc.org/


> So does anyone know of any evaluation of the longevity of the expression for

> UT1?


In short, they find a current difference of around 0.2 s that will
grow at a rate of about 1/365.25 * DeltaT

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