Observations "Panoramic view of the entire near-infrared sky reveals the distribution of galaxies beyond the Milky Way . The image is derived from the 2MASS Extended Source Catalog (XSC) —more than 1.5 million galaxies, and the Point Source Catalog (PSC)--nearly 0.5 billion Milky Way stars. The galaxies are color coded by ' redshift ' obtained from the UGC , CfA , Tully NBGC, LCRS, 2dF , 6dFGS, and SDSS surveys (and from various observations compiled by the NASA Extragalactic Database ), or photo-metrically deduced from the K band (2.2 um). Blue are the nearest sources (z < 0.01); green are at moderate distances (0.01 < z < 0.04) and red are the most distant sources that 2MASS resolves (0.04 < z < 0.1). The map is projected with an equal area Aitoff in the Galactic system (Milky Way at center)."  Another indicator of large-scale structure is the ' Lyman alpha forest '. This is a collection of absorption lines which appear in the spectral lines of light from quasars , which are interpreted as
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This note was uploaded on 12/15/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.