[LEAPSECS] BBC radio Crowd Science

[Steve Allen]

On Wed 2017-02-01T10:50:12 -0500, Brooks Harris hath writ:
> Yes, well its that "fundamentally ambiguous" part that none of us
> can stand and keeps us obsessed with the LEAPSECS discussion, I
> guess.

If only we lived in a woulda, coulda, shoulda world we might have had
a clear prescription for how things work.

Around 1950 the IAU decided that there would be two time scales, a
new, uniform Ephemeris Time, and the old wobbly Universal Time.
D.H. Sadler wrote a precient paper about the changes, gotchas,
caveats, mathematical techniques, geometric meaning, and long
implications for astronomy, time keeping, and notions of longitude.
He laid out just about everything about how to work with two time scales.
	Ephemeris Time
	D.H. Sadler
	Occasional Notes of the RAS v3 #17 p103 (1954 October)
	http://adsabs.harvard.edu/abs/1954ONRAS...3..103S
That is by now a really obscure publication, and some of the
implications were recently revisited in
	The Mean-Solar-Time origin of Universal Time and UTC
	J.H Seago, P.K. Seidelmann
	Advances in the Astronautical Sciences 148:1789-1807 (January 2013)
	http://www.agi.com/downloads/resources/white-papers/AAS_13-486.pdf

In 1969 Sadler was aware of the CCIR plan to implement leap seconds.
In the report prior to the 1970 IAU meeting he raised serious
objections about the handling of leap seconds by automated systems,
particularly aircraft collision avoidance systems.
http://adsabs.harvard.edu/abs/1970IAUTA..14..343Z
But at the IAU meeting in 1970 it was announced that CCIR had not sent
the IAU any official communication about the leap second, so the IAU
could make no official response prior to its implementation.
http://adsabs.harvard.edu/abs/1971IAUTB..14..193W

Histories from Greenwich say that Sadler subsequently wore black on
days when leap seconds were to happen, and he wrote his own memoir
http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1978QJRAS..19..290S
in which he coined the term "International Time" as a better idea for
radio broadcasts than UTC with leap seconds.

In retrospect it is pretty clear that folks running the radio
broadcast time signals based on atomic chronometers wanted to rush the
leap second into existence without broad consideration of the
implementation details or long term implications.  They are later in
the record lobbying CGPM, national governments, and other agencies to
adopt UTC with leap seconds as the perfect solution for time.

--
Steve Allen                    <sla at ucolick.org>              WGS-84 (GPS)
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