Supergalactic coordinate system
A supergalactic coordinate system are spherical coordinates that have their equator aligned with the supergalactic plane .
This level is characterized in the closer universe around the earth by the distribution of nearby galaxy clusters such as the Virgo galaxy cluster , the great attractor and the Pisces-Perseus supercluster . The supergalactic plane was recognized by Gérard-Henri de Vaucouleurs in 1953 in the Shapley-Ames catalog . The planar distribution of nebulae was noticed by William Herschel more than 200 years earlier .
It is defined that the supergalactic longitude and latitude are denoted by SGL and SGB, in analogy to l and b in galactic coordinate systems . The zero point of supergalactic longitude is defined as the intersection between this plane and the galactic plane.
Definitions
- The supergalactic north pole (SGB = 90 °) lies at the galactic coordinates l = 47.37 ° and b = + 6.32 °. In the equatorial coordinate system ( epoch J2000), this is close to RA = 18.9 h and Dec = + 15.7 °.
- The zero point (SGB = 0 °, SGL = 0 °) is at l = 137.37 ° and b = 0 °. In J2000 equatorial coordinates this is approximately RA = 2.82 h and Dec = + 59.5 °.
See also
Web links
- Precise definition by Lahav et al. 2000, MNRAS, 312, 166, bibcode : 2000MNRAS.312..166L