NavList:

I agree with Frank that the possibility that the horizon may be a high altitude cloud bank makes calculating refraction highly problematic since it will depend on index of refraction at layer forming the horizon.

It is not clear to me that there was an actual difference in what was being said about the effect of refraction by Greg, Marcel and myself. I think it was a language problem about the "what" of what was bigger and what was smaller. In any event as Frank points out we ought to ignore refraction. I have not done the calculations on dip but I suspect that the change in earths radius by a cloud bank will not appreciably affect the dip.

Once the stars in the field of view around the moon have been identified,an SHA Dec coordinate system can be established and the moon assigned values of SHA and Dec. The moon position in SHA and Dec will have to be corrected for the parallax of the radius of the earth and the altitude of the space station. With corrected moon SHA and Dec an almanac will produce GMT and GHA of moon.

Sun and moon could define direction from moon (GHA, Dec) but not very precisely. And since moon is close to horizon coordinates of our position will again be very inaccurate.

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