As Compiled by

Barry F. Madore and Ian P. Steer

NASA/IPAC Extragalactic Database (NED)
California Institute of Technology
The Observatories
Carnegie Institution of Washington
Pasadena CA
With generous support from the Carnegie Institution of Canada

(Version Date: October 20, 2008)


We present the NASA/IPAC Extragalactic Database of Distances. This is the third public release.

NED-1D (NED1D) provides 3,716 accurate, contemporary distances to 1,073 galaxies with modest recessional velocities (that is, less than 1/8 c) published between almost exclusively 1990 and 2006

NED-4D (/level5/NED4D) gives distance to objects at cosmologically significant redshifts (z greater than 1/8 c)

NED-0D (/level5/NED0D) provides a listing of over 200 distances exclusively for the Large Magellanic Cloud.

NED-0.5D (/level5/NED0.5D) six (RA ordered) files provide 15,231 secondary distances to 4,762 galaxies

1. Introduction

Extragalactic distances, first measured in a modern way by Henrietta Leavitt (1912) and Edwin Hubble (1926) using Cepheid variables, have had a profound impact on our view and understanding of the local Universe and cosmology. Before NASA's launch of the Hubble Space Telescope (HST), only a dozen or so such distances were known with confidence (see, for example Freedman 1988). Since HST (and its refurbishment) the number has exploded. Summarizing some of that growth Ferrarese et al. (2000) compiled and published a database of 235 accurate distances to 107 galaxies. More recently, Karachentsev, Karachentseva, Huchtmeier & Makarov (2004) have produced a catalog of 451 galaxies, including 274 with accurate distances (and an additional 177 with distances based solely on redshift or cluster membership). Before NED-1D, most astronomers, including Masters et al. (2004) assumed accurate distances were available for several hundred galaxies, a number supported by the largest previous extragalactic distances database (containing 1,300 distances, of which several hundred are accurately determined, Giudice 2005).

Here, we have attempted to meet the need for an up-to-date and easy-to-use, tabulation of accurate, contemporary extragalactic distances. It is designed to support scientists, space missions and ground based observatories in the planning, interpretation and publication of research on galaxies, extragalactic distances, and cosmology. NED-1D will be maintained, with revised and updated versions being made available on a regular basis.

2. Main Objectives

The primary goal of NED-1D is to provide both amateur and professional astronomers with a means of rapid and efficient access to a comprehensive ensemble of published distance measurements, tightly linked to the primary literature, through an easy-to-use, on-line spreadsheet.

In its first implementation NED-1D provides

- one-stop retrieval of thousands of accurate extragalactic distances published and available online from 1990 to 2006, along with their bibliographic references;

- direct hyperlinks to the richer datasets and resources in NED proper;

- help in preparing proposals for future observations.

In future releases NED-1D will grow in size and scope in a series of already planned updates, extensions and upgrades, providing users with new capabilities, as described in Section 5 (below).

3. How Does NED-1D Work?

Our primary source for published data on distances to galaxies was the NASA Astrophysical Data System (ADS), examining papers published from 1990 to a present cut-off for Version 1.0 of NED-1D of Jan. 1, 2006. Papers containing relevant key words in their abstracts (such as "galaxies" and "distances") along with key words relating to any of ten main distance determination methods (e.g.- "galaxies distances Cepheid," and "galaxies distances supernova", etc.) have been searched for, extracted and examined.

In its initial release (Version 1.0, June 21, 2006) NED-1D provides 3,065 accurate distances to 1,073 galaxies with recessional velocities less than 1/8 c (37,500 km/s). These have been extracted from a compilation of 329 contemporary papers. In the current version of NED-1D the galaxies are listed by RA order and each distinct distance measurement is given its own individual row (as many galaxies now have numerous distance determinations based on a variety of methods). For each distance, one can easily retrieve the following data, gain hyperlinked access to the originating literature and further data within NED as follows:

Galaxy Name:

Column 1, this entry is hyperlinked to NED proper and allows rapid access to all of NED's published data on each galaxy, including basic data, relevant papers, images, charts, redshifts, photometry, diameters and more.

Galaxy Distances:

Columns 2 to 13, show published distances (given uniformly in kiloparsecs (kpc) for reasons of readability and ease of formatting). Column 2, summarizes the quoted distances; Columns 3 to 12 are distances as determined by distinct methods. The ten main methods chosen to be highlighted in these columns are:

1. Cepheid: based on the Cepheid Periodicity-Luminosity Relation
2. TRGB: Tip of the Red Giant Branch (I-band luminosity function cut-off)
3. PNLF: Planetary Nebula Luminosity Function
4. GCLF: Globular Cluster Luminosity Function
5. SBF: Surface Brightness Fluctuations (I-band)
6. SNIa: Supernova Type Ia
7. BS: Brightest Star Luminosities
8. Sosies: "Look-Alike" galaxies
9. TF: Tully-Fisher relation
10. FP: Fundamental Plane

In Column 13, we present distances determined by other less known or highly specialized methods. In Column 14, we encode those methods numerically: No. 1 to 10 for the main methods (above), and No. 11 to 36 for others (as given below):

11. Proper Motions
12. Eclipsing Binaries
13. Masers
14. RR Lyrae Variables
15. Red Clump
16. HII Region Diameters
17. Type II Supernova (optical)
18. Type II Supernova (radio)
19. Globular Cluster Radii
20. Novae
21. Color-Magnitude Diagrams
22. Blue Supergiants
23. Absolute Magnitude of the Horizontal Branch
24. Giant Branch Fitting
25. Long-Period Variables and Miras
26. RSV Stars
27. Carbon Stars
28. BWC Stars
29. Post-Asymptotic Gaiant Branch Stars
30. Globular Cluster Surface-Brightness-Fluctuations
31. Globular Cluster Fundamental-Plane
32. Globular Cluster Dynamics
33. Delta Scuti Stars (High Amplitude)
34. White Dwarf Cooling Sequence
35. Sub-Dwarf Fitting
36. M Stars

Distances Bibliographic Data:

Column 15 gives an internal reference #. Column 16 gives the standard NED/SIMBAD REFCODE, and is hyperlinked to the original paper and sources on-line.

Supplementary Data: Galaxy Positions and Properties:

The J2000 equatorial coordinates, Galactic coordinates, Hubble type, and recessional velocities with respect to the Milky Way Galactic Standard of Rest (GSR), are generated automatically from NED, and shown for reference in Columns 17, 18, 19, 20, 21, and 22, respectively. These quantities are given for completeness and convenience only; they are meant to be fiducial rather than definitive. Finally, another internal tabulation number #, for future sorting and error correcting appears in Column 23.

4. Current Status

NED-1D is currently available exclusively through LEVEL 5: A Knowledgebase for Extragalactic Astronomy and Cosmology (NED1D). Work is underway to incorporate these data into NED directly such that distances (when available) will be displayed for individual galaxies.

5. NED-1D Updates and Future Versions

Designed for maximum flexibility, current planning allows for astronomers and users to specify the exact nature of future updates and upgrades. We anticipate a primary need for NED-1D to provide a new, minimum baseline for the number of accurate distances known, and to be ready just in time to begin assimilating the many thousands and soon tens of thousands of accurate distances that will inevitably be published after launch of NASA's next-generation, James Webb Space Telescope mission in 2013 (see, Gardner et al. 2006). In addition to maintaining up-to-date information, via future updates as customer specified, we anticipate user needs for additional versions of NED-1D, as part of an overall NED-D system. A complete system will provide additional distance information not currently included, and incorporate other distances, not now provided. Areas of future interest have so far been categorized into the following, potential versions.

5.1.1 NED-0D

To provide accurate, contemporary distances to the Large Megallanic Cloud (LMC), the extragalactic distance scale zero point based on Cepheids. NED-D's "Level 0" distances now exceed 200 in number, based on more than 20 methods, published since 1990.

5.1.2 NED-0.5D

To provide 10,000+ distances to 5,000+ galaxies based on less accurate but widely applied methods, not included in NED-1D unless backed up by accurate methods, but including large numbers of distances based on Tully-Fisher, Fundamental-Plane, and other methods, and combining multiple large survey/compilation catalogs, such as the "Nearby Galaxy Catalog" (Tully 1988), and "Catalog of Neighboring Galaxies" (Karachentsev et al. 2004), into a meta-catalog of "Level 0.5" distances.

5.1.3 NED-1D

Provides more than 3,000 accurate, contemporary distances to over 1,000 galaxies as published from 1990 to January 1, 2006. Listed in order of Right Ascension.

5.1.4 NED-2D

To provide distances from NED-1D in more detail, including published distance moduli and their individually quoted uncertainties, as well as explicit corrections, if any, for reddening (foreground and target), age (metallicity or color), distance-scale zero point, distance-scale formula (e.g. - PL relation), photometric zero point, and cosmological model (e.g. - Hubble constant). To account for these various sources of distance correcting differences between contributors, NED-2D will produce homogenized distances. By adjusting NED-1D's published distances to what they would be if all contributors were working from the same set of assumptions, NED-2D distances will attempt to level the extragalactic distances playing field.

5.1.5 NED-3D

To provide published distances from NED-1D and/or calibrated distances from NED-2D, using galaxy pairs, groups, clusters and supercluster membership, as well as non-associated "field" galaxies. NED-3D is intended to provide a basis for sorting out "peculiar" or non-Hubble velocities, based on the departures observed between the recessional velocities and distances of ~ 150 galaxy pairs, dozens of groups and clusters, and the two nearest superclusters, which now have 702 distance estiamtes to 145 galaxies in the Virgo supercluster and 293 distance estimates to 70 galaxies in the Fornax supercluster.

5.1.6 NED-4D

To provide distances to galaxies with recessional velocities greater than 1/8 c, currently totaling 183 distances to high redshift galaxies based on SNIa distances published since 1990.

5.1.7 NED-5D

To document hundreds of distance estimates to several dozen galaxies, as published before 1990, and going back to de Sitter (1917), who guessed, more than estimated, that Andromeda, NGC 1068, and NGC 4594 were all at then astounding sounding distances of 100 kpc.

6. Summary

NED-1D, 4D and 0D are on-line databases of accurate extragalactic distances designed to support scientists in their research, from proposal to publication. Accurate extragalactic distances, as well as basic galaxy properties are included along with pointers to the distances bibliographic references, complete with hyperlinks enabling rapid access to the full range of other data and resources available within NED proper for these and other galaxies. The primary goal of NED-D, in addition to serving as an extragalactic distances database, is to provide a portal to the community of scientists working on galaxies, offering quick access to most of the other published data and resources available on galaxies.

7. Final Thoughts

This collaboration once again demonstrates the strong synergy that can be exploited between amateur and professional astronomers. We hope that it is seen as a positive example for future collaborations.


de Sitter, W. 1917, Mon. Not. Roy. Astron. Soc., 78, 3

Ferrarese, L. et al. 2000, Astrophys. J. Suppl., 128, 431, astro-ph/9910501

Freedman, W. L. 1988, Astron. Soc. Pac., 1988, 4, 24

Gardner, J. P. et al. 2006, accepted by Space Science Reviews, astro-ph/0606175

Giudice, G. 2005, A Compilation of Nearby Galaxies Distances, online database, see:

Hubble, E. P. 1926, Astrophys. J., 64, 321

Karachentsev, I. D., Karachentseva, V. E., Huchtmeier, W. K. & Makarov, D. I. 2004, Astron. J., 127, 2031

Leavitt, H. S. & Pickering, E. C. 1912, Harvard College Observatory Circular, 173, 1

Masters, K. L., Haynes, M. P. & Giovanelli, R. 2004, Astrophys. J. Lett., 607, 115L, astro-ph/0404455

Tully, R. B., Nearby Galaxies Catalog, Cambridge University Press (Cambridge, 1988)