locked Re: Moon Dx #general


I recently looked into this. There is no simple answer. The Apogee and Perigee vary considerably over time.
See the following paper from NASA:


Over the period 2008-2010, the radius of the orbit varies between 356,568 and 406,602km.
Over a 5000 year period, it varies between            356,355 and 406,725km.
It depends on what the programmes have assumed...

Julian, G3YGF

On 26/09/2022 00:52, w6de wrote:
They could all be correct depending on the assumptions. Your position on the earth and the distance to the to the moon constantly varies. Examine what each of the three programs assume for the reflection point on the moon and your position on the earth.

Dave, w6de

-----Original Message-----
From: main@WSJTX.groups.io <main@WSJTX.groups.io> On Behalf Of Michael Black via groups.io
Sent: Sunday, September 25, 2022 22:31
To: WSJTX Group <main@wsjtx.groups.io>
Subject: [WSJTX] Moon Dx #general

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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