On Sat 2014-01-11T21:43:02 -0800, Brooks Harris hath writ: > Any help getting to the bottom of this appreciated.
It's history, and it's confused. Measurement techniques were crude and people were not cognizant that there was more than one thing being measured. Measurement techniques are vastly improved and some people understand better, but even the best current knowledge cannot unconfuse the folks in the past or be sure how to interpret their understanding using a modern vocabulary and reference frame. NASA technical report number 70 by Hans D. Preuss of the Department of Geodetic Science at Ohio State University "The Determination and Distribution of Precise Time" is relevant to read to see how badly confused the situation was in the 1960s http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19670028967_1967028967.pdf NIST has many of the old NBS publications scanned and online at their website, and many of the announcements of rationales and dates when decisions were made to change the radio broadcasts are scattered among those. Their publication with most dense collection of such facts is NBS Monograph 140 which can be found at http://digicoll.manoa.hawaii.edu/techreports/PDF/NBS140.pdf But nobody is going to reset their clocks based on a new understanding of when an epoch was nor what kinds of seconds were being counted. Tabulating historic differences between the values of various time scales is of little relevance to the decision before the ITU-R. How they handle the leap second issue will assert whether humanity has any intent of keeping the meaning of the word "day" to be based on the rotation of the earth. -- Steve Allen <s...@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m _______________________________________________ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs