The aim of this section of the course is to familiarise you with celestial Coordinates. ... I found some good notes explaining the celestial coordinate system on the web: . ... 1st Dec: 04hr, 00min In addition to the equatorial coordinates described in the notes above, astronomers also use (at least) two other coordinate systes: galactic coordinates and ecliptic coordinates. ... Ecliptic coordinates use the ecliptic (the Earth's path around the sun) as the equator, and are used for solar system work. ...