Is skyfield.data.horizons consistent and up to date?

[roe-dl]

In the Skyfield documentation in What is the angular diameter of a planet, given its radius? the radius is set as a constant in the script. Is there a way to retrieve that radius out of the ephemeris loaded into eph in that example or from some other source supported by Skyfield?

[roe-dl]

I recently found the file skyfield.data.horizons that contains some planet radii. There is a function festoon_ephemeris(ephemeris) that I found nowhere in the manual. Additionally, the values differ from some I found at NASA's website.

heavenly body	skyfield.data.horizons [km]	equatorial radius [km]	source of the latter value
Sun	695500.0	696342	https://iopscience.iop.org/article/10.1088/0004-637X/750/2/135
Mercury	2440.0	2440.5	https://nssdc.gsfc.nasa.gov/planetary/factsheet/mercuryfact.html
Venus	6051.8	6051.8	https://nssdc.gsfc.nasa.gov/planetary/factsheet/venusfact.html
Earth	6371.01	6378.137	https://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html
Mars	3389.9	3396.2	https://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html
Jupiter	69911.0	71492	https://nssdc.gsfc.nasa.gov/planetary/factsheet/jupiterfact.html
Saturn	58232.0	60268	https://nssdc.gsfc.nasa.gov/planetary/factsheet/saturnfact.html
Uranus	25362.0	25559	https://nssdc.gsfc.nasa.gov/planetary/factsheet/uranusfact.html
Neptune	24624.0	24764	https://nssdc.gsfc.nasa.gov/planetary/factsheet/neptunefact.html
Pluto	1195.0	1188	https://nssdc.gsfc.nasa.gov/planetary/factsheet/plutofact.html

You see, for Venus the value in skyfield.data.horizons is the same as the equatorial radius provided by the NASA. In contrary, for Uranus the value in skyfield.data.horizons agrees with the mean radius provided by the NASA. Similar for the other planets.

No data is in skyfield.data.horizons about the Moon (equatorial radius 1738.1 km, polar radius 1736.0 km, mean radius 1737.4 km according to https://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html) and Ceres (equatorial radius 487.3 km, polar radius 454.7 km, mean radius 476,2 km according to https://www.nature.com/articles/nature03938).

What about skyfield.data.horizons and its usage?