NASA -the 4 Coordinate Systems

NASA reference from Chrome search for Supergalactic Coordinates system

follows

What's relevant for me is the equinoxes disappear as valid points of

reference when coordinates frameworks leave behind our solar system

(read bottom)

Un4nKp15BfY/dereferrer/?redirectUrl=https%3A%2F%2Fned.ipac.caltech.edu>

Four coordinate systems are supported by the near-position (cone)

search. The coordinate systems are Equatorial, Ecliptic, Galactic, and

Supergalactic. The Equatorial system gives declination (Dec) measured

relative to the celestial equator, set by the Earth's rotational axis at

either the B1950.0 or J2000.0 equinox (the two most commonly used). The

right ascension (RA) in this system is measured in hours, minutes, and

seconds, relative to the first point of Aries, where the ecliptic

crosses the equator at the specified equinox. The Ecliptic system gives

latitude measured relative to the ecliptic, defined by the projection of

Earth's orbit around the sun. The longitude in this system is measured

in hours, minutes, and seconds, relative to the first point of Aries.

The Galactic system gives latitude measured relative to the Galactic

plane and longitude measured relative to the Galactic center. The

Supergalactic system is defined relative to the plane of the Virgo

Supercluster. Note that changing the Equinox has no effect for the

Galactic or Supergalactic systems."

An equinox has no effect for the Galactic or Supergalactic systems