[time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

[Mark Sims]

A 30 cm daily vertical offset is pretty typical.  I've seen over 45 cm.   Horizontal offsets are usually less than +/- 75 mm per day with the longitude displacement typically twice the latitude displacement.

Heather uses a standard model  (see http://geodesyworld.github.io/SOFTS/solid.htm) to calculate earth tides.   
I converted the Fortran code to C and use a more accurate routine for calculating sun and moon positions.  The gravity calculation code is from TVB's code.

Actual tides experienced at a given location depend can depend upon locally unique factors like underground geology and nearby bodies of water.  Compensating altitude for an optical clock would be considerably more complex.

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> You're place really moved a foot in 48 hours? Impressive and scary!