So what you are saying is every 30 years select a new leap CS reference. Dispense with everything in between.
On Fri, May 11, 2012 at 2:21 PM, Tom Van Baak <t...@leapsecond.com> wrote: > > 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. > > Hi Peter, > > Everyone should take ten seconds and look at this animated GIF: > http://leapsecond.com/pages/ut/ut-ani-v2.gif > > It shows what would have happened to "earth time" vs. "atomic time" if the > cesium frequency had been defined to be other than 9192.631770 MHz. As > you can see a slightly higher number would have meant less deviation > between the two timescales. > > However it should also be clear, even with this short 40-year plot, that > no number is the best or correct or right choice. It all depends on which > year(s) you choose to base your earth rotation rate calibration on (the > astronomers doing the calibration in the 1950's selected the year 1900 as > their baseline). > > To see each page at your own pace here is it as a multi-page PDF file: > http://leapsecond.com/pages/ut/ut-ani-v2.pdf > > If you wanted a near perfect match between atomic time and the rotation of > the earth during the 1970's hindsight tells you the frequency should have > been 9192.632080 MHz. Similarly if your crystal ball said to use > 9192.632010 you would have been very close for three decades. If you > wanted the best time accuracy from the year 1972 to present you should have > picked 9192.631950. > > /tvb > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.