Extragalactic Atlas Overview

The Extragalactic Atlas has fewer groups than the Milky Way Atlas, mostly because there is less variety of objects outside galaxies than inside them—galaxies and quasars make up much of the data available for the Extragalactic Atlas. In the table below, we list these data groups along with a brief description and a reference to a detailed description. The order of the groups is the same as one finds in the Digital Universe.

**Table 4.1:** Extragalactic Atlas data groups with brief descriptions. Follow the hyperlinks to a detailed description of each group.
Group Name	Description
`stars`	The observed stars (on a fixed sphere)
`constel`	Constellation connectivity lines
`mwVis`	Visible all-sky survey
`radec`	Celestial (RA/Dec) coordinates
`galac`	Galactic coordinates
`galaxy`	An image for the Milky Way
`halo`	The Galactic halo
`local`	Galaxies near the Milky Way
`Tully`	Tully Galaxy Catalog
`isoDensity`	Tully's smoothed density surfaces
`2MASS`	2MASS Galaxy Catalog
`Abell`	Abell galaxy clusters & nearby superclusters
`2dFgals`	The Two-Degree Field Galaxy Survey
`SloanGals`	The Sloan Digital Sky Galaxy Survey
`2dFQSOs`	The Two-Degree Field Quasar Survey
`SloanQSOs`	The Sloan Digital Sky Quasar Survey
`wmap`	WMAP all-sky survey (cosmic microwave background)
`100kly`	A 100,000-light-year grid centered on the Sun
`1Mly`	A 1 million-light-year grid centered on the Sun
`10Mly`	A 10 million-light-year grid centered on the Sun
`100Mly`	A 100 million-light-year grid centered on the Sun
`1Gly`	A 1 billion-light-year grid centered on the Sun
`20Gly`	A 20 billion-light-year grid centered on the Sun

In the following sections are a series of primers for those new to extragalactic astronomy. Addressing questions like, ‘What is a galaxy or quasar?’ or ‘What is large-scale structure?’, these sections will bring you up to speed on galaxies and cosmology.

If you know about galaxies, quasars, and cosmology, you can skip ahead to “Extragalactic Atlas Tutorial,” where we explore these groups in the context of the Atlas and the Universe.

Subsections

Digital Universe Atlas

Digital Universe Guide

Extragalactic Atlas Overview

Extragalactic Atlas Overview