[time-nuts] Why 9,192,631,770 ??

[paul swed]

OK I have learned a lot and absolutely fantastic news.
No matter what my aged CS says I can claim its accurate now. Its simply the
world has not caught up to or slowed down to it.
Regards
Paul

On Fri, May 11, 2012 at 2:30 AM, mike cook <michael.cook at sfr.fr> wrote:

> Le 11/05/2012 07:14, Peter Monta a écrit :
>
>  Are there better estimates of the ET second nowadays (relative to the
>> SI second)?  It would be interesting to know what the cesium frequency
>> "should have been" if much better estimates of the ephemeris-time
>> second were available at the time.  One would think that with all the
>> solar-system data JPL and others have had at their disposal since the
>> 1970s, a very good ET-second number could be cooked up; better than
>> 1950s Moon cameras at any rate.
>>
>
> There are various refs in the pedia to later estimates. Markowitz (1988)
> calculated an agreement to 1x10-10.  but looking at the article I see there
> were still some uncertainty in terms used to calculate ET and depending on
> what was chosen gave 2x10-11 .  Accordingly he concludes conservatively
> that ET has been equal to Si within 1x10-9.
> The uncertainties will have been reduced since then but not eliminated and
> so "should have been"  is a moving target but it would appear from the
> above that the chosen SI value would still be preferred if the decision was
> to be reappraised.
>
>
>
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