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Old October 27th 17, 01:50 PM posted to sci.astro.amateur
Martin Brown[_3_]
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Default Time and timekeeping

On 26/10/2017 14:12, Gerald Kelleher wrote:
On Thursday, October 26, 2017 at 9:13:32 AM UTC+1, Martin Brown
wrote:
On 25/10/2017 18:59, Gerald Kelleher wrote:


The theorists assume they are discussing time when it is really
timekeeping they are referring to. Of course this goes back to a
person who decided to define timekeeping as time itself using a
calendar based facility known as the Equation of Time -


The equation of time is just the first order correction for a whole
host of other effects that alter the spin of the Earth. The transit
of the sun makes for a very poor time standard by comparison with a
star.


This is a foolish statement, the 'Equation of Time' is a timekeeping
facility that only works within the calendar framework so before the
theorists so running after a notion that 'clocks measure' time, the
job of a clock is merely to maintain a constant pace in terms of the
AM/PM cycle or its subdivisions of hours,minutes and seconds. The


The problem (even from antiquity) is that our clocks became more
accurate than the motion of the sun. In antiquity the Babylonians were
aware that the sun moves across the sky at a variable rate which was
quite an achievement with the naked eye instruments of the day.

Over 2 thousand years later you still haven't grasped those basics.

Our atomic clocks now maintain insane accuracy such that the seasonal
change in the moment of inertia of the Earth as the leaves fall from
northern hemisphere trees is detectable in the discreprancy between
(atomic) terrestrial dynamical time and the rotation of the Earth.

IERS Bulletin C ann the prediction of leap seconds is online he

http://hanksville.org/futureofutc/pr...522_Gambis.pdf

Genuine astronomers might enjoy reading it.

--
Regards,
Martin Brown