[LEAPSECS] Fractured fairy tale

Rob Seaman seaman at noao.edu
Thu Dec 23 10:09:58 EST 2010

Poul-Henning Kamp wrote:

> Broadcast time *IS* civil time, it is broadcast as a service to civilians.

Robust engineering does not confuse implementations with standards.

More fundamentally, civil timekeeping has its own requirements distinct from scientific or technical timescales. These requirements are less stringent in different regards, perhaps, but are no less real or ultimately binding. In innumerable ways civil time is required to remain what it always has been, a timescale layered on mean solar time. One can only cheat time for a little while.

Which is to say that mean solar time is a requirement. Leap seconds as we currently know them are one possible way to implement that requirement. The latter is negotiable. The former is not.

Rather than attempting to subvert requirements, proper system engineering builds on a scrupulous accounting of the requirements as they are. The documentary justification needed for a system implemented with significant liens is far greater than the justification necessary for a system whose engineers chose candidly to adhere to the actual requirements.

The ITU proposal on the other hand is devoid of any justification whatsoever. The system engineering plan that should accompany such a substantial change to a fundamental standard is completely absent. There are no white papers providing an analysis of the effects of severing civil timekeeping from mean solar time. There is no discussion of the varied mitigation that will be needed for diverse purposes and communities. No inventory of affected systems - we know absolutely that astronomical software will suffer, are there other such examples? There isn't a scrap of paper corresponding to anything a stakeholder such as an engineer might consult.

Proponents of the proposal appear to regard this utter lack of supporting documentation as a feature - a feature perhaps of the rough-and-tumble real-world politics of international standards-making. Rather it is simply an astonishing and embarrassing lack.

The Emperor has no clothes - and his fob watch is running backwards.

Rob Seaman
National Optical Astronomy Observatory

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