[LEAPSECS] it's WP7A week in Geneva

[Poul-Henning Kamp]

In message <AB352DD8-FFDB-4CCF-A582-C7DB12163C5F at noao.edu>, Rob Seaman writes:


>I have (tediously, bombastically, endlessly) asserted that civil time  

>IS solar time.  This is a statement of requirements.  Requirements  

>describe the problem space.


And you have repeatedly tried to ignore the question of how large
the civil-solar tolerance is, can or should be.

I would estimate that the majority of the worlds population are not
within one hour of solar time at any point in the year.  China, for
instance, is one single timezone.  

But maybe part of that problem is in the moniker "civil time",
which we have never fully agreed what means ?


How about we operate with _three_ kinds of time and one kind of geophysics:

"Timekeeping Time":  What timekeeping scientists work with, for keeping
time.  Mind you: "Time", not 'Earth Orientation".  Today this would
be TAI, TAL etc.

"Earth Orientation":  A set of physical parameters describing the
motion of this planet, including its rotation.  Today this would be
UT, UT1, UT2, and half of UTC.

"Scientific/Technical Time":  What computers and scientific experiments
use internally, in order to be able to communicate temporal
relationships unambiguously.  Today this is UTC + Leap-second table
+ Leap-second announcement.

"Human time": What people see on their clock.  Today that is usually
UTC, fuzzed by political concepts such as DST.


Obviously, Neither ITU nor BIPM has any control over what "Human
Time" is or how it works.  National and federal lawmakers decide
that, often illadvisedly, and occationally very stupidly.   China,
as I recall, is one single timezone, and some places countries have
30 minute offsets from UTC I belive.  If any national government
wants to do something stupid to human time in their country, nobody
can prevent them from doing so.


Timekeeping Time and Earth Orientation should be left to the
scientists, and should obviously be established and maintained as
precise as funding will allow.  UN and ITU has no mandate in this
area, so the relevant organizations (IAU etc) are free to do as
they please.


What is left then, is the Scientific and Technical time.

Which is exactly what UTC was intended to be originally, and why
the definition and possible redefinition of UTC happens in an obscure
technical corner, of a UN organ most people have not heard about.


Now, please make your argument, that Scientific and Technical time
should be polluted by earth orientation parameters ?

Yes, it would be convenient for astronomers pointing their telescopes,
but do you have any other argument than that ?


Poul-Henning

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