Jeb - the calculations are pretty easy -Mariners have to adjust the Marine Charts for this polar shiftevery year - the amount of correction is 6 seconds per year 1 degree = 60 minutes; 1 minute = 60 seconds, therefore 1 second is 1/3600th of a degree per year.
However I only used 2004BCE as the original pic was taken in 2004CE.
For those who would like an accurate plan of the stones then may I oblige you?
This is a half size version of the one it links to so click on it for full size. You will see that there is a very small angle between the existing Heel stone and the location of the site of the second stone. There are 56 Aubrey Holes in the outer stone circle making each an angle of 6deg 25' 42.86" apart (6.4285714 degs - divide by 2 = 3.2142857 pi= 3.1415927 coincidence in similarity?) - this angle from the very centre allows both stones to be visible in the gap between the three Aubrey holes that are in line with the heel stones, the centre Aubrey lining up with...... er starting to let the cat out of the bag again. Zzzzzzzipppp. :lol: