[time-nuts] Chilean quake shifted Earth's axis. The length of the day shorter by 1.26 microseconds ?

Henry Hallam henry at pericynthion.org
Tue Mar 2 05:32:52 UTC 2010


Of course... I am designing a GPS receiver as my day job and didn't
think of that ;)

Henry

On Mon, Mar 1, 2010 at 8:36 PM, Mark Sims <holrum at hotmail.com> wrote:
>
> Pretty trivial to do with GPS where a 1 ns error is under 1 foot of position error (and a geodetic grade GPS can give sub-millimeter accuracy)...  even a cheap consumer grade unit is under 10 feet of error.   1.26 us of orbital change is over 1100 feet of error.
>
> One trick is to compare the pre-earthquake GPS almanac/ephemeris data with the post earthquake data.  I suspect that a lot of geodetic monitoring stations are scrambling to keep up with what the earth is currently doing.
>
>
> ---------------------------
> How would one go about verifying this? The angular difference after 1
> year is about 3E-8 radians, which is probably well beyond the absolute
> pointing accuracy of any telescope, and swamped by lunar tidal
> deceleration anyway.
>
>
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-- 
Henry Hallam

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