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Dear Frank:
You wrote:

> Yesterday, October 29,...
> First I did a series of index correction sights
> off the Moon.

Why did not you use the Sun?

> Carefully aligning the Moon images pole-to-pole, my
> observations were (on arc, off arc):
> 33.1, 31.7
> 32.9, 31.3
> 32.7, 31.4
> 32.8, 31.2
> Subtracting and averaging, I settled on
> an index correction of -0.75
> minutes of arc.

Adding and averaging gives 64.275.
While according to the Almanac, true Moon SD
for October 29 was 15.8, which gives 4DS=63.2.
So you are off by the whole minute.

So much of the Lunar IC correction.
Or do I confude something?

I just tried to repeat this experiment with
IC from the Moon. After VERY careful measurement
I obtain
On: 32.3, 32.4, 32.3, 32.2
Off: 33.5, 33.6, 33.5, 33.6.
This gives 4SD=65.85, while the true 4SD this evening
is 65.2 where I took the average SD between
October 31 and November 1 because it is about midnight
in Greenwich now.

The result is off by 0.6.

Now I derive from my data IC=0.7 which also seems absurd.
From stars I found today that IC is close to zero,
and this is confirmed by a reasonably good Lunar.

So I am very skeptical about using the Moon for
IC correction.

Alex.


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