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 George-
Separately from the question of whether the apparent lunar speed affects the 
accuracy of lunars, I'm curious as to this question of motion. I've never 
spent a night measuring the moon's position so I've never really looked into 
this.

The moon orbits around the earth, counterclockwise, approximately once every 28+ days.
The earth rotates on its axis, counterclockwise, once every 24 hours.
The earth rotates in orbit around the sun, counterclockwise again.
As do the planets...out there.

Now, I mention this last (the planets) because the I am familiar with the fact 
that an apparent RETROGRADE motion of the planets against the stars is caused 
by the parallax due to the relative orbital motions of the Earth and other 
planets. If orbital parallax (pardon the phrase) can cause an apparent 
reversal of motion, I can readily concede that it can cause a change in 
apparent speed as well.

But I must confess, with all the corkscrewing through space (moon, earth, 
rotations, orbits, ALL of them) I've got no grasp on the magnitude of the 
actual angular errors and amounts of "speed" that the sum total of all these 
motions would cause. I have to wonder if someone wouldn't need to program the 
whole mess into a computer to run out the numbers that actually show the sum 
totals of error caused by all these motions, because I can only see that 
trying to run down actual numbers will be quite complex.

Is there anyone on the list with access to that type of data, or up to that magnitude of task?

Separately, as I've said, from the issue of whether this can actually make a 
difference in the overall human task of taking and clearing a lunar. (In 
other words, if the difference is less than one second of time, I'd consider 
that to be impossible accuracy and as such ignorable.)

   

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