[LEAPSECS] Get off my lawn!

[Steve Allen]

On 2011 Jun 18, at 09:31, Tom Van Baak wrote:

> Are the details about UT1 correct in this link?

> http://hpiers.obspm.fr/iers/bul/bulb/explanatory.html

> 

> I ask because a number of posters claim UT1 is a measure of

> earth angle. At one level this is true, of course, but if I read that

> document correctly it says that certain periodic terms have been

> removed from UT1. I think that's where the confusion arises -- it

> makes UT1 seem more like it's trying to be a clock and less like

> a precise measure of angle.

> 

> Perhaps you can clear up the mystery.


It's mostly for practicality and utility.
The document indicated there
ftp://hpiers.obspm.fr/eop-pc/models/interp.readme
gives much of that story.

The values of UT1 are published no more often than daily, so
in order to facilitate interpolation the higher frequencies are
removed from the published values with the expectation that the
user will interpolate within the day and then add the high
frequencies back.

Such a user is likely to be involved with pulsar timing or VLBI
or high precision satellite geodesy.

--
Steve Allen               <sla at ucolick.org>              WGS-84 (GPS)
UCO/Lick Observatory      Natural Sciences II, Room 165  Lat  +36.99855
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