Supergalactic coordinate system

A Super Galactic coordinate system are spherical coordinates, which have aligned their equator on the super galactic plane.

This level is distinguished from the surrounding universe around the earth through the distribution of nearby clusters such as the Virgo cluster, the Great Attractor and the Perseus Pisces supercluster. The super galactic plane has been detected in the Shapley - Ames catalog of de Vaucouleurs Henri Gérard - 1953. The planar distribution of nebulae, however, was noted more than 200 years earlier by William Herschel.

It is defined that the super galactic longitude and latitude by SGL and SGB are called, in analogy to l and b in galactic coordinate systems. The zero of the super galactic longitude is defined as the intersection between this plane and the galactic plane.

Definitions

• The super galactic north pole ( SGB = 90 °) is located at the galactic coordinates l = 47.37 ° and b = 6.32 °. In the equatorial coordinate system (epoch J2000 ), this is near RA = 18.9 h and Dec = 15.7 °.
• The zero point (SGB = 0 °, SGL = 0 °) is located at l = 137.37 ° and b = 0 °. In J2000 equatorial coordinates, this is approximately RA = 2.82 h and Dec = 59.5 °.