thank you for this enlightening report.

In message: <[EMAIL PROTECTED]>
            Steve Allen <[EMAIL PROTECTED]> writes:
: On Wed 2007-01-17T12:31:14 -0700, Warner Losh hath writ:
: > It has been remarked that the current state of the art is that 100ms
: > accuracy can be predicted about a year in advance only and that the
: > models are constantly undergoing refinement.  It has been estimated
: > that IERS could issue leap seconds, with today's technology, about 3-5
: > years out and still be in a 95% or 99% band of certainty that the 0.9s
: > margin is maintained.  However, I can't find papers that show these
: > models or point to any better data than hearsay...
: The best that I know of were the ones presented at the Colloquium that
: the WP7A SRG held in Torino in May 2003.  There was a time when the
: host institution (IEN) was providing the proceedings online, but the
: contents of that URL went away sometime around a year ago.  (I wonder
: if they may not have liked the conclusion that was reached.)
: In the spirit of promulgation I provide what they once did at
: The conclusion was originally a powerpoint drafted in real time, it is
: The indications of how well predictions of UT1 might be done are found
: in three presentations to which Felicitas Arias contributed.
: There are two which were powerpoint
: and one which is a more verbose writeup of one of the powerpoints

I like figure 8, that shows that 20ms steps lead to 50ms steps lead to
100ms steps lead to 1s steps. :-)

I also like the quotes:

"Dating in UTC is ambiguous when a positive leap second occurs in
systems other than those using hours, minutes and seconds; in this
latter system the use of second "60" may a cause of difficulty."


"Thus UT1 is not, strictly speaking, a form of solar time"

Also, did I miss figure 9 in arias_3?

Proposal II has gotten much press here (the leap hour one), but
Proposal I sounds a lot like what I've suggested: Use TAI time and let
countries move the time zones when they feel like they no longer are
close enough, but it kinda omits that last part...


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