[LEAPSECS] How good could civil timekeeping be?

Steve Allen sla at ucolick.org
Thu Feb 14 16:07:54 EST 2008

On Thu 2008-02-14T14:07:52 +0000, Tony Finch hath writ:

> How does the mean solar day relate to ephemeris time?

Again, the interval when the worst chaos reigned as people tried to
figure out how to answer that question is covered in this 1966
document by the geodesist trying to explain it all for NASA.

The scholarly record in the refereed journals, the long sequence of
publications by the BIH, and references in the works by Guinot point
to a treasure trove of material by Stoyko that must be in the BIPM
and/or Paris Observatory from the interval of history when this was
being grokked.

For a shorter version see Seidelmann's writeup in
Explanatory Supplement to the Astronomical Almanac,
University Science Books, 1992

For another short version see the Metrologia paper by Nelson et al.
The leap second: its history and possible future, v38, #6, pp509-529, 2001
I think there are aboutt three copies out there on the web.

For another insider's view see the book by Audoin & Guinot
The Measurement of Time: Time, Frequency and the Atomic Clock
Cambridge, 2001

For the long view see all the annual publications of the BIH and the
USNO regarding their work with radio signal time sync. Also the
triennial publications of the IAU general assemblies with focus on
the output from commission 31, especially the proceedings from the
late 1950s through early 1970s.

For those with access to material not yet available try the book being
written by McCarthy and Seidelmann for publication by Wiley. I
suspect it will be very good.

If anyone knows of any memoirs of this sort penned by Markowitz then I
would not be alone in really wanting to learn about them.

The words from the 1964-08-28 meeting of IAU commission 31 have
remained true over more than 40 years:
La distinction entre epoque et intervalle de temps n'est pas
claire pour tous.

There is a distinction. POSIX zoneinfo and its equivalents in other
precison+civil time systems already have the mechanisms to let the
distinction be clear. They can handle both a monotonic interval and a
conversion to and from various epochs that corresponds to externally
mandated standards. The question is whether or not we want to insist
on broad cognition of that distinction, or whether we'll dumb down
reality for the sake of simplicity.

Steve Allen <sla at ucolick.org> WGS-84 (GPS)
UCO/Lick Observatory Natural Sciences II, Room 165 Lat +36.99855
University of California Voice: +1 831 459 3046 Lng -122.06015
Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m

More information about the LEAPSECS mailing list