[LEAPSECS] LEAPSECS Digest, Vol 45, Issue 1

Ian Batten igb at batten.eu.org
Thu Sep 2 14:26:03 EDT 2010

On 2 Sep 2010, at 18:37, Rob Seaman wrote:


> For just one instance, the proposal is not only to cease leap

> seconds, but to cease the reporting of DUT1

Could you clarify that? DUT1 is surely produced by IERS, who aren't
accountable to the ITU, and propagated by (as examples) WWVB and MSF,
which are accountable via NIST to the US government and via NPL to the
UK government. I assume the other nationally operated time sources
have similar governance. I'm not sure how the ITU could stop MSF
from reporting DUT1.

But if you drop leap seconds in UTC, DUT1 relative to "new UTC" will
rapidly exceed 0.9s, which breaks everything that consumes those
signals and, for example, breaks astro-navigation unless somehow the
format is fixed to allow for |DUT1|>0.9. It would also make the
issue of precisely what UK time is a live issue again, because rather
than the difference between de jure GMT and de facto UTC being
"classic DUT1" which is for legal purposes negligible, it would start
to get distinctly noticeable as "new DUT1" grew larger (assuming a
means to propagate it).

Why would the UK government accede to this just because the ITU say
so, and not just align UTC(NPL) to "UTC classic" and declare leap
seconds itself (based on DUT1 predictions, as today)?

It would be interesting to produce a list of countries where legal
time is not UTC, to see what the divide would look like. Wikipedia
claims Belgium, Canada and Eire: for extra fun, I bet most consumers
of time signals in Belgium use DCF77 or TDF, which are clearly in UTC
land, rather than MSF.


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