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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