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I would like to be able to find mean node of a planet/satellite.

It is quite different from this question in the sense that I am looking for nodes between the mean ecliptic of a date and the moon (or any other celestial body, but let's stay simple)

"mean of date (or sometime MOD)" as http://nsdb.imcce.fr/multisat/Descripe.html describe it:

Mean of the date (IAU76): The satellite astrometric coordinates given in ICRF are converted to the equator and equinox of the date with the precession model adopted by IAU in 1976.

I understood that skyfield use ICRF positions. I suspect the date.P internal value of skyefield (compute_precession(jd_tdb) ? or any other ?) have to be used to get to the expected value of the mean latitude of date.

But how ?

Ones finally getting the mean latitude of date the rest of the process to get the time of nodes have already been well described by Brandon Rhodes , so I guess no need to talk about this part.

If possible I would like to use skyfield or at least use python.

As I am not trained yet to those "transformations, reference frame.." business; Any help will be used and much appreciated.

stackcats
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Skyfield itself doesn't currently implement the IAU76 precession model because IAU76 is out of date and not as accurate as more recent precession models.

Could you update your question to outline why the '76 precession model is of particular interest to you, and why nodes between the Moon and the mean ecliptic are of particular interest to you? That might help us recommend more specific approaches.

Alternatively, you might try asking your question on https://astronomy.stackexchange.com/ since it's not exactly a programming question — you don't have sample code that you don't understand or need fixed — but seems like a more general question about how to approach an astronomical puzzle?

Brandon Rhodes
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