(12-17-2015, 04:00 PM)stargazer Wrote: I'm relatively ignorant about celestial navigation but I understand the major motions of the celestial bodies fairly well. So here is my best guess of what the V in the correction tables stands for.
Velocity - just my guess. And here is my reasoning. We are orbiting the sun, and the major corrections are based on the sun. Since we orbit the sun it's apparent movement is mainly determined by the earth's rotation, with some variation due to the fact that when closer we have to rotate a bit farther to catch up to the same local position. Draw a curved path and the earth and move it, you will probably see what I mean.
The planets however are quite close astronomically speaking and since they are also revolving around the sun they have not just the earth's rotation effect, but there own motion around the sun. So their motion in addition to the earth's rotation has to be accounted for.
On the outer planets their motion is in the same direction as the moon, but slower since further away.
Venus is a special case (Mercury always too low on the horizon to be used). Venus's orbit is inside the earth's orbit, so at times it's motion should appear to reverse. And being both close to us, and close to the sun, it's apparent motion is quite rapid, compared to the outer planets. So it's correction should be both larger and reversing.
I've not looked at the tables, this is just my best guess.
V technically should not stand for velocity, since velocity means both speed and direction, but that is still my best guess.
I'll be happy to learn from anyone who really knows.
The "v" stands for variation which is specific to GHA hourly variation.
Pretty simple.