[tz] Coordinated Universal Time (UTC) to retain “leap second”
marshall.eubanks at gmail.com
Fri Nov 20 18:31:21 UTC 2015
On Fri, Nov 20, 2015 at 1:12 PM, Steve Allen <sla at ucolick.org> wrote:
> On Fri 2015-11-20T12:55:49 -0500, Marshall Eubanks hath writ:
> > No, that will not work. The UTC clock is providing not just the time, but
> > also the rotation of the Earth (UT1). An atomic clock cannot do that (not
> > at the km level), and the tables cannot provide leap seconds (much) in
> > advance.
> The almanacs are tabulated only a couple of years in advance, and over
> that short an interval the current predictions of earth orientation
> have errors about the same as the typical human error using a sextant.
The USNO's MICA runs up to 2050, but of course does not include future UT1
> Full precision already needs the DUT1 = UT1 - UTC, so if the radio
> broadcast time signals and almanacs could arrange to agree on a new
> time scale then a new difference value would preserve that ability.
> Well, you could get WWV to announce UT1 - UTC offsets :)
But, then, you couldn't do celestial navigation off-shore with an FM or AM
Full disclosure, Marshall and I worked across the building from each
> other using VLBI to measure earth orientation, so take this discussion
> as an example of why the ITU-R could not forge a working compromise.
It does tend to give rise to discussion...
> Steve Allen <sla at 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
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