[ntp:questions] National time standard differences

unruh unruh at wormhole.physics.ubc.ca
Tue Feb 9 22:56:59 UTC 2010

On 2010-02-09, David Woolley <david at ex.djwhome.demon.invalid> wrote:
> David J Taylor wrote:
>> I remember the flying of caesium or other atomic clocks round the world, 
>> and that folks had to invoke relativistic corrections.  Were these 
>> better than microseconds as well?

The flying of clocks around maryland was primarily a test of the special
relativistic corrections. For a distant sattelite, the General relativistic and
special relativistic are essentially the same size ( because the speed
of the sattelite is determined by the gravitational field of the earth).

And both are in the PPB range-- and are cumulative(ie give a frequency
shift to the clock rate. If it is a circular orbit that is it. If it is
elliptical, then there is in addition a small periodic clock rate
change. A PPB over an hour gives microsecond shifts in the time. 

> That's called Navstar (GPS) and GPS position solutions do have to 
> include a general relativity correction to the satellite clocks.

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