NASA / IPAC Extragalactic Database

While catalogs like Messier or the NGC are like curated "best-of" albums, the NASA/IPAC Extragalactic Database (NED) is the entire Library of Congress for everything outside our Milky Way. It is a massive, living digital archive that serves as the ultimate clearinghouse for extragalactic data.

History & Who Made It

NED was established in 1990 and is operated by the Infrared Processing and Analysis Center (IPAC) at the California Institute of Technology (Caltech), under contract with NASA.

It was created at the dawn of the digital age to solve a "data explosion" problem. As space telescopes like Hubble and Spitzer began sending back millions of data points, astronomers needed a single place where every piece of information about a specific galaxy—its name, its distance, its chemical makeup, and its photos—could be unified and searched instantly.

The Purpose: The "One-Stop Shop" for Galaxies

The primary purpose of NED is cross-identification and data fusion.

• Name Resolution: A single galaxy might have 20 different names. NED links them all so you know they are the same object.

• Bibliographic Linking: If a scientist in Japan writes a paper about a specific galaxy, and a scientist in Germany takes a radio photo of it, NED links those together.

• Calculators: NED provides "Cosmology Calculators" that allow astronomers to input a galaxy's redshift () and determine how far away it is and how fast it is moving away from us.

What Information Can Be Found In It?

NED is not just a list; it is a multidimensional database. As of 2026, it contains data on over one billion distinct objects.

The Data Breakdown:

• Positions & Names: Precise coordinates and every known catalog alias.

• Redshifts (): Over 5 million spectroscopic redshifts, essential for mapping the 3D structure of the universe.

• Photometry: How bright the galaxy is in every "color" from high-energy Gamma rays to low-energy Radio waves (the Spectral Energy Distribution).

• Images: Millions of FITS images and previews from surveys like SDSS, GALEX, and 2MASS.

• Distances: Thousands of independent distance measurements (using Cepheid variables, Supernovae, etc.).

NED Database Summary

Catalog Name: NASA/IPAC Extragalactic Database (NED)

Established: 1990

Host: IPAC / Caltech

Total Objects: >1 Billion

Content: Galaxies, Quasars, Supernovae, and Gravitational Lenses.

Core Functions:

1. Search by Name: Find everything known about "Messier 51."

2. Search by Location: Find every galaxy in a 1-degree circle around a specific point.

3. Search by Parameter: Find all galaxies with a specific redshift or brightness.

How to Use It (For Amateurs and Professionals)

NED is free and open to the public at ned.ipac.caltech.edu.

• For the Amateur: If you find a faint "smudge" in your astrophotography and it doesn't have an NGC number, you can plug the coordinates into NED. It will tell you exactly what that galaxy is, how far away it is, and provide a link to every scientific paper ever written about it.

• For the Professional: It is an essential tool for "Big Data" astronomy. Before a researcher applies for time on the James Webb Space Telescope, they check NED to see what has already been discovered about their target.

NED vs. SIMBAD

Observers often get NED confused with SIMBAD (run by the CDS in France). The rule of thumb is:

• SIMBAD: Primarily for objects inside our Milky Way (Stars, Nebulae, Planets).

• NED: Exclusively for objects outside our Milky Way (Galaxies, Quasars).

Version 2016

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