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In correspondence with George about a lunar distance measurement I made with Jupiter recently I wrote:-

Having the LD 'clearing' now so easily available on calculator, I tried a
ten minute increase in altitudes (one side then the other) with a fixed LD to see what happens to the cleared LD, and can confirm it only made a difference in the third decimal place in degrees, equiv to less than two tenths of a minute of arc.

Hence the maxim from old that the altitudes are not so critical as the lunar distance measurement itself. This is of course intuitively obvious too, as the two zenith distances of the "sides" of the polar spherical triangle from the
pole to Moon, and pole to star can change a bit "up or down" without
changing the distance between the two points much at all.

Douglas Denny.
Chichester. England.
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