[LEAPSECS] A leap second proposal to consider -- LSEM

Rob Seaman seaman at noao.edu
Thu Nov 4 16:39:47 EDT 2010

We often get lost on this list in the details of legal or physical timescales. Astronomers need to know such details. Civilians need a simple mechanism. The current civil timescale cleverly provides access to both interval time and a measure of mean solar time in a single pragmatic realization of both. Forget all the higher mathematics - heck, professional timekeeping is often only known after the fact. Does that describe any wall clock you know?

If civil time is remade without the half that provides knowledge of Earth orientation, then access to that information will be required in some other manner. It is patently obvious that the ITU does not consider this their problem. If they want to pawn this requirement off on some other group, the bare minimum price of entry is for the changes to TF-460 to instantiate a new timescale with the characteristics THEY want, such that OTHERS can build coherently and competently a new mechanism to convey mean solar time. That is - universal time - that is, something that has derived with minimal fuss and muss from the rich history of UTC, GMT, and earlier timekeeping standards.

To minimize the fuss, choose a different damn name. This is what was agreed in Torino in 2003. There will still be fuss, but it will (perhaps) be manageable.


On Nov 4, 2010, at 1:23 PM, Michael Deckers wrote:


> On 2010-11-03 23:31, Steve Allen remarked:


>> I see the point of "mean solar time" not as "how accurately does the

>> expression represent the sun over the earth?" but as "does the

>> expression even try to represent the sun over the earth?".

>> I think that the discussions and intentions surrounding the current

>> draft revision of TF.460 indicate that it does not try.


> Yes, you are of course right. My point is that even UT1

> does not try. Sidereal time is no longer an affine

> function of UT1.


> Michael Deckers.

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