Redshift-Independent Distances in the NASA/IPAC Extragalactic Database: Methodology, Content and Use of NED-D

Understand

Estimates of galaxy distances based on indicators that are independent of cosmological redshift are fundamental to astrophysics.

• Researchers use them to establish the extragalactic distance scale, to underpin estimates of the Hubble constant, and to study peculiar velocities induced by gravitational attractions that perturb the motions of galaxies with respect to the Hubble flow of universal expansion.
• In 2006 the NASA/IPAC Extragalactic Database (NED) began making available a comprehensive compilation of redshift-independent extragalactic distance estimates.
• A decade later, this compendium of distances (NED-D) now contains more than 100,000 individual estimates based on primary and secondary indicators, available for more than 28,000 galaxies, and compiled from over 2,000 references in the refereed astronomical literature.