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Mark - I thought I posted this yesterday but probably pressed the wrong button. Anyway I couldn't resist the Lunars bit, so for what it's worth here's my doggerel which I'm sure you can improve with your poetic pen or ignore as you wish.

Regards

Bob C

That is toward or away

Oh, dear me, I’ve just found,

My trusty clock has not been wound!

If only I had checked it sooner,

Now, like Josh, I must do a Lunar.

Our Moon is not just a great big rock,

She also functions as an accurate clock.

There are no hands for us to read

But She moves at quite some speed.

On Ecliptic plane we find a planet or star,

And from Selene have to find how far.

Put our trusted sextant on its side,

And measure distance far or wide.

Now this number we must make clear,

But at such hard sums we quake with fear.

Worry not, we can correct this arc,

With clever tables from Bruce Stark.

Our Almanac tells us what values are fair,

With these the cleared arc we can compare.

If all has thus been properly construed,

We know, near enough, our Longitude.

Thus ends here my tale of woe