LEDA was created in 1983 at Lyon Observatory. Since this time, the database has been continuously updated and improved. The main goal is to collect raw measurements from published observations and to archive them. The connection to LEDA is obtained through the Internet network:
telnet lmc.univ-lyon1.fr
login :leda
From LEDA it is possible to extract the most important astrophysical
parameters for more than 95,000 galaxies.
(e.g.: cross-identifications, coordinates,
morphological description, diameters, axis ratio, surface
brightness, flux at different wavelength, 21-cm line width,
central velocity dispersion, group membership, radial velocities).
Each parameter is given with bibliographic reference and basic
characteristics of the measurement.
Additional parameters are
also available from LEDA. Two kinds of such parameters are
defined: statistics-dependent and model-dependent parameters.
From statistical analysis, raw measurements
are converted into mean homogeneous parameters. The method
is exactly that initiated by G. de Vaucouleurs and his
co-workers when he published his famous series of catalogues RC1, RC2
and RC3.
Many useful parameters are calculated using only well accepted
models.
These parameters are: galactic and
supergalactic coordinates, inclination, galactic and internal
extinction, corrected diameters, magnitudes, colours,
velocity corrected with respect to various systems, kinematical and
photometrical distance moduli, absolute magnitude, etc.
2D-information can also be obtained either on the screen with the X-interface
or as postscript files. Thus, you can get charts, Flamsteed's equal area projections or true images of the field.
Powerful tools are provided to users: X-interface for visualizing
2D-information, SQL-like language for extracting data in a very versatile way,
Batch mode for easy use, etc.
For instance, in batch mode the user has just to send
an e-mail to
ledamail at lmc.univ-lyon1.fr
with the list of his objects (Names or 1950-coordinates)
giving a Subject adapted to the requested
task (e.g., LIST, FLAMEQ).
These parameters are regularly distributed on a standard CD-ROM allowing the user to work with a PC computer or an independent workstation.