NavList:

Dear Lars,

I went for "very accurate altitudes" to give a fully meaningful example, or at least the "picture" which goes around it.

Nonetheless, even if altitudes are not required to be as accurate - which has long been taught in Classical Lunar courses - the only fact that you are using such usual "classical" variables, i.e. 2 heights and a Lunar Distance, implies that you are implicitly considering a "moving observer" in the sense I described it, whether or not you are solving your Lunar the way which has been described here.

That is one handy and convenient way to verify that and to understand why under this view-point the LD rate of change is [always] bigger when altitudes are constrained to remain constant - i.e. for a "moving observer" - than for a Observer steady on Earth.

Your last conclusion is of course very good : if both bodies share the same azimuth, it is very valid to use their altitudes difference which can be expected to be very close from their sextant observed LD.

Kermit