On Mon 2019-03-25T16:54:28-0700 Tom Van Baak hath writ: > In retrospect we would have had fewer leap seconds if they had > chosen 9192631950 Hz instead of 9192631770 Hz. But at the time it > wasn't a choice; it was just a measurement.
And it was a measurement which was performed during an interval when everyone was surprised by the data they were seeing. Around the beginning of 1957 the rotation of the earth's crust shifted suddenly as seen in the USNO plot of UT2 at the bottom of https://www.ucolick.org/~sla/leapsecs/amsci.html At the time that the paper giving 9192631770 was published nobody was sure whether this was an actual change in the earth or some failure to understand cesium frequency standards. It was a few years before it had become clear that earth rotation has a power spectrum of random fluctuations. Over time the BIH had the opportunity to watch cesium vs. Ephemeris Time for more years than the original papers. In 1964 Anna Stoyko found a value of the cesium frequency 9192631799 Hz w.r.t. Ephemeris Time (Bulletin Horaire ser 6 no 7 p 186). -- Steve Allen <s...@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.