On Fri 2024-05-24T15:33:23-0700 Paul Eggert via tz hath writ:
* africa (Africa/Maputo), europe (Europe/Zurich): Add #STDOFF comments for two zones with well-sourced standard time that was not an integral number of seconds away from UT. This does not change the TZif output files.
I urge great caution for the use of subsecond offsets. In 1853 some observatories were still calculating their time using tables of the motion of earth which were based on recent observations of the sun, whereas other observatories had begun to use tables of the motion of earth based on perturbation theory where the mean sun was calculated over an interval of millennia where the resonance 3*Jupiter - 8*Mars + 4*Earth (with a period of about 1850 years) moved the mean mean sun 0.5 time second away from tables based on recent observations of the sun. As late as the 1920s the tabulations of received time signals in BIH Bulletin Horaire show that different radio broadcasts of Universal Time differed from each other by 0.2 time second or more. Even as late as 1958 the USNO radio broadcasts differed from the BIH value of UT2 by 0.03 time second because the values USNO used for its longitudes and the values BIH used for longitudes were not expressed in a globally consistent reference frame. -- Steve Allen <sla@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