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In the Python Skyfield library there is a position object skyfield.positionlib.ICRF, in the documentation it states:

An (x,y,z) position and velocity oriented to the ICRF axes.

The International Coordinate Reference Frame (ICRF) is a permanent reference frame that is the replacement for J2000. Their axes agree to within 0.02 arcseconds. It also supersedes older equinox-based systems like B1900 and B1950.

From my minimal knowledge in surrounding these topics this look to be a typo? I cannot find a reference or any documentation relating to the "International Coordinate Reference Frame" only to the "International Celestial Reference Frame".

Also based on what I've read/learned about the International Celestial Reference Frame the documentation from Skyfield seems to be describing just that. Further leading me to believe this is a typo.

Can anyone clarify if the "International Coordinate Reference Frame" is an actual thing?

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The quotation correctly (though not completely) describes the International Celestial Reference Frame, so I'm comfortable calling "Coordinate" a typo.

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    $\begingroup$ Assuming the OP is somewhat familiar with version control software or using github they should create either a pull request or an issue. Correcting typos is an acceptable commit. The typo Coordinate is used twice in the library and is probably copy-pasted. Otherwise Celestial is used. github.com/skyfielders/python-skyfield/blob/… github.com/skyfielders/python-skyfield/blob/… $\endgroup$
    – RomaH
    Sep 15, 2022 at 6:41
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    $\begingroup$ Better than a pull request is to submit an issue and make sure it really isn't what the author intended. Do the pull request after that. $\endgroup$ Sep 15, 2022 at 17:05

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