locked Re: Moon Dx #general

Charles Suckling

Hi Mike

I forgot to add, that discrepancies may arise between programs that use a 6
character grid locator to define your home location, and JPL Horizons where
you can enter your exact location, due to the potential inaccuracy in
determining your exact location from a 6 digit Maidenhead locator.

We see this sometimes on microwave EME, where the computed Doppler shifts
may be a few Hz out. Similar effects might well happen with moon
distance. Its all negligible, however!



On Mon, 26 Sept 2022 at 10:57, Michael Black via groups.io <mdblack98=
yahoo.com@groups.io> wrote:

I had an older version of PSTRotator and they agree much better now with
17.28 -- differing by around 100km as of right now so only 0.026% between

WSJTX 390620
PSTRotator 390506
MoonCalc 386676

MoonCalc is now the odd one out and off by approx 3900km but I imagine
they are doing the orbital distance and not surface-to-surface.

Mike W9MDB

On Sunday, September 25, 2022 at 06:51:13 PM CDT, Svend, OZ7UV <
spanget@...> wrote:

Hi Mike.

I just got this answer:

PstRotator v17.28.
The displayed Moon distance is now the distance between your location and
the Moon surface.
It is still a difference around 100km between PstRotator and WSJT-X, and I
will try to find the reason.

Codrut - YO3DMU
\Svend, OZ7UV

man. 26. sep. 2022 01.02 skrev Michael Black via groups.io <mdblack98=

Trying to determine accuracy of moon distance.

Using WSJTX Astronomy window, PSTRotator and https://www.mooncalc.org

All 3 seem to agree pretty well on Az and El but distance is off by about
5000km comparing WSJTX to the others.

As of 13:00 or so I see
WSJTX 383,115
PSTRotator 388074
MoonCalc 388199

The equatorial radius of the moon is 1,738km so that doesn't explain the
difference (of about 1.3%).

It seems the code in wsjtx was done with certain deliberation so I'm
hoping WSJTX is more accurate. But how to resolve who's right?

Mike W9MDB

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