HYPERLEDA introduction
leda Introduction to HyperLeda site

| HyperLeda home | Documentation | Search by name | Search near a position | Define a sample | SQL Search |

HyperLeda is an information system for astronomy: It consists in a database and tools to process that data according to the user's requirements. The scientific goal which motivates the development of HyperLeda is the study of the physics and evolution of galaxies.

LEDA was created more than 20 years ago, in 1983, and became HyperLeda after the merging with Hypercat in 2000. At present the database contains over 3 million objects, out of them 1.5 million are certainly galaxies (with a high level of confidence). See the distribution of the galaxies on the sky.

HyperLeda is now developed in the general frame of the Virtual Observatory, a concept by which astronomers around the world will have access to any kind of data available in the web on their desks. Users will submit queries which will transparently extract and process data from different servers throughout the world and return the result in an standardized form.

The Virtual Observatory and HyperLeda are also of a major interest for education and popularization of astronomy.

HyperLeda distributes a variety of services:

The user interface, on the web, allows sophisticated searches in the database with many links to other resources. The main functionalities are:
For more details, questions, or in case of problems, do not hesitate to contact us: leda@univ-lyon1.fr

Access to HyperLeda

HyperLeda may be freely downloaded and installed on Linux/Unix platforms, but the easiest access is through the WEB. There exist several mirrors:
In some cases it is useful to access HyperLeda with scripts or to customize the output (to fit the needs of a particular application). The advanced user's guide provides informations about these possibilities

Current contents

The database is build around several compilations which are then used to produce and homogeneous description of the galaxies. This homogenization consists in converting the original measurements to a standard scale, to reject wrong measurements and to compute a representative average.
The list and description of homogenized astrophysical parameters is available here and more details on the homogenization process here

List of compilations

The list of references for data included in the HyperLeda compilations is here.


The people presently actively involved in the operation of the database are:
Some other colleagues are occasionally involved or were associated in the past

Using, reporting errors and acknowledging HyperLeda

Access and data provided by HyperLeda can be freely used, and the software is distributed under the Open Source GNU Public License. Usage of services and/or data is warmly encouraged.

HyperLeda does not guarantee the absence of error in the original data, in their processing or in the software used to retrieve them, but the HyperLeda team is very interested in reducing the number of these errors.
You would help us very much by reporting the errors you meet. Please send us an email: leda@univ-lyon1.fr describing as precisely as possible the problem that you found.

The acknowlegments are crucial in order to continue to provide public access to the database. If you use HyperLeda to prepare observations, define a sample, or for any other purpose, please

A report of the usage made of HyperLeda would also help us to improve the service.

We encourage to report us the usage of data or services in any application as popular astronomy papers, web sites, softwares, catalogues... This would allow us to grant personalized support. We are maintaining a list of applications using HyperLeda.


The HyperLeda project and the catalogues are presented in the following papers (this is not a complete list):

Special thanks to:

This database has been developed with the help of many people:
Andernach H., Becker M., Bottinelli L., Buta R.J., Corwin H.G.Jr., Davoust E., de Vaucouleurs A., de Vaucouleurs G., Courtois H., Durand N., Fouqué P., Garnier R., Kogoshvili N., Gouguenheim L., Hallet N., Lanoix P., Mamon G., Marthinet M.C., Miyauchi-Isobe N., Rouaix S., Rousseau J., Simien F., Odewahn S., Takase B., Vauglin I., Watson, C., Winner R..
and the following Institutions : 
MENST, INSU, PNG, PNC, CNRS, DRED, Conseil Régional Rhône-Alpes, Observatoire de Lyon, Observatoire de Paris-Meudon, Centre de Données de Strasbourg (CDS), ATP.
We make use of the ESO facility in Munich for retrieving images from the Digitized Sky Survey produced at the Space Telescope Science Institute under US Government grant NAG W-2166. It is based on photographic data obtained using The UK Schmidt Telescope and the Palomar Sky Survey.

HyperLeda Questions: leda@univ-lyon1.fr