CfA Redshift Catalog
The universe is expanding, carrying galaxies with it like flotsam on a fast-flowing river. This expansion also stretches the wavelength of light, which astronomers call cosmological redshift, since it pushes visible light colors toward the red end of the spectrum. That means astronomers can determine the distance to far-away galaxies by measuring the redshift of light they produce. The CfA Redshift Catalog (ZCAT), created by researchers at the Center for Astrophysics | Harvard & Smithsonian, is a clearinghouse for historical redshift data from a number of observatories, including the 1.5-Meter Tillinghast Telescope and the MMT Observatory, both CfA-operated telescopes located at the Fred Lawrence Whipple Observatory (FLWO) in Arizona. This data provides a map of galaxies in three dimensions, allowing astronomers to piece together how galaxies group on the largest scales in the universe. ZCAT is an essential resource for data on redshift surveys up to 2008, carrying on the legacy of the original CfA Redshift Surveys conducted in the 1970s and ‘80s.