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Following Kermit's explanation of his usage of the word "unrefracted", to
mean-
"that's what the altitude would be if the atmosphere didn't refract it"? ,

now I can answer his question about clearing a lunar. He suggested there
were two possibilities for dealing with the two altitudes involved-

"- either they are just corrected for sextant error (for the same reasons
as
here above, no possibility for a more "resonable" assumption) and in such
case we have to process them as such,

- or they are unrefracted topocentric because, to the best of my knowldge -
and thank you for any correction here - , that was the form (i.e. Body
Center Unrefracted Topocentric) which was then required to carry out most
conventional Lunar Clearings."

Not the second alternative, because the clearing process itself is to
correct for the effect of parallax and refraction of the observed bodies on
the lunar distance.

And not the first alternative, because dip wasn't mentioned.

What's needed is altitude corrected for index error and dip, but for
nothing else.

(although the correction process itself isn't at all fussy about the exact
details of those altitudes, so in truth, it would matter little how, or if,
such corrections had been applied).

I suggest that Kermit is concentrating on aspects of a lunar distance that
do not matter. But I'm aware that he is a fellow who is keen on exactitude.

George.

contact George Huxtable, at  george@hux.me.uk
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.

----- Original Message -----
From: "Antoine Couette" 
To: 
Sent: Tuesday, March 30, 2010 12:05 AM
Subject: [NavList] Re: AW: Sun Moon Lunars to 155 degrees


George, you just wrote :

" from George- I'm unsure what Antoine means by the word "unrefracted".
Does
that mean "there's no correction been made for refraction"? Or does he mean
"that's what the altitude would be if the atmosphere didn't refract it"?
Sorry if I'm being stupid. "

My reply is as follows :

Unrefracted meant exactly : " "that's what the altitude would be if the
atmosphere didn't refract it"? ".

And there are no stupid questions, but only incomplete previous
explanations. So, I am happy that you raised this point.


Thank you also for all your last comments.


Nite time for me now ...


Kermit
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