On Mon 2019-01-21T22:00:16+0000 Michael Deckers hath writ: > [things that amount to wishful thinking that reality was simple]
The pages of Bulletin Horaire reveal that time is nowhere near as simple as we would wish. https://www.ucolick.org/~sla/leapsecs/bhpages.html > Do you happen to know in which tabulation the jump by 1.6 ms > occurs? A3 minus which other time scale? The jump of 1.6 ms is clear in the tablulations of UT2 - A3 done by both Stoyko and Guinot, and both of them point it out. It was an inevitable side effect of changing from FK3 to FK4. It means that all reported values of UT2 from before 1962 must be adjusted if the desire is to have everything in a single homogeneous system. Stoyko and Guinot did not choose to do that. Curiously there is not a big jump in the value of UT2 - A3 at that same date which would have been caused by changing from the old expression for UT2 - UT1 to the new expression. I surmise that this means Stoyko and Guinot did correct the old values of UT2 for the change in that formula. But more surprising is an obvious change in the rate of both tabulations of UT2 - A3 at 1961-01-01. This leaves me wondering if the fix for the change of UT2 formula was done not by recomputing UT2-UT1 for all past values, but simply by subtracting the difference on that new years day. The answer to this deserves a close look at whether the slope difference matches the difference in the old and new UT2 expressions, and also a close look at the BIH annual reports to see whether they indicate the acquisition of computing machinery. -- Steve Allen <[email protected]> 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 _______________________________________________ LEAPSECS mailing list [email protected] https://pairlist6.pair.net/mailman/listinfo/leapsecs
