NavList:

In addition to my last post, where I indicated the value of "32.0s UT / 0.1' LD ratio" from a known position, I am to say that computing from a steady (i.e. non moving) position is equivalent to computing such a ratio with definitely variable heights, which vary mainly as the result of the local hour angles changes of both Moon  (about 14.5°/h) and Procyon (close to 15.0°/h).

I also added " I trust that the "32.0s UT / 0.1' LD ratio" derived herabove could be improved if one were using the classical method instead." . YES, definitely so ! The classical methods make use of constant heights, here 40°29' for the Moon and 10°19' for Procyon. Hence, given the constraint of non changing heights, the "classical" methods implicitly assume a moving observer who moves at a rate such that the constrained / constant heights remain constant.

Accordingly, the LD change rate as seen from a moving observer has no reason to be the same as from a non moving observer.

Approximate example for this case :

Non moving observer at N47°/E010° i.e. implicitly variable heights

UT = 03:30  Moon LL Hs = 39°23.732' / Az = 092.2°    Procyon Hs = 09°11.977' / Az = 092.2°   LD = 30°11.755'

UT = 03:38  Moon LL Hs = 40°43.568' / Az = 093.7°    Procyon Hs = 10°33.227' / Az = 093.7°  LD = 30°10.341'

LD rate of change : 0.1' / 33.9s

Constants heights, implicitly moving observer (with longitudes changing at 15°/h and overlapping fixed observer at 03:34)

UT = 03:30 N47°/E011° Moon LL Hs = 40°04.999' / Az = 092.9°   Procyon Hs = 09°52.483' / Az = 092.9°   LD = 30°12.516'

UT = 03:38 N47°/E009° Moon LL Hs = 40°02.231' / Az = 092.9'   Procyon Hs = 09°52.705' / Az = 092.9°  LD = 30°09.526'

LD rate of change : 0.1' / 16.0s

Therefore all view points are fully reconciled :

- Through considering constant heights - implicitly moving observer - the LD rate of change is close to 0.1' / 16.0 s of elapsed time. The resolution of UT would be around 17 seconds per tenth of a minute of arc

- Through considering a non moving observer, the LD rate of change is close to 0.1' / 32.0 s of elapsed time .  The Moon Limb / Procyon closure rate is slightly under 2.0' during a 10 minute elapsed time.

 Hope this clarifies these concepts. It explains why we get in both cases very valid results, simply because we are not comparing LD rates in the same environment.

That should also now bring a final explanation and word to our so-called "parallactic retardation" earlier furious debate ...

I think that everybody was 100% right then.

Simply different concepts were discussed.

We now fully see why there were different in essence: LD rates of change are different if seen from a fixed point on Earth or if seen from a moving Observer, a configuration which is implicitly implied with the use classical methods based on non-changing heights.

Kermit