Re: OT 10Mhz references

Craig Sawyers <c.sawyers@...>

This is the earth's geoid - the surface of constant gravitational and rotational potential energy, and
represents the surface that water would take under that influence. It gives a good visualisation of
what GPS has to correct for.

There are more accurate gravitational maps from GRACE and GOCE missions, but the datasets are on a
commercial basis.

Hi David,
You are correct. It has proved to be extremely difficult to measure frame dragging and it is too
small to
have an effect on the GPS satellites.

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