Astron. Astrophys. Suppl. Ser.
Volume 124, Number 1, July 1997
|Page(s)||109 - 122|
|Published online||15 July 1997|
VII. Reduction of astrophysical parameters
CRAL-Observatoire de Lyon, UMR 5574, F-69230 Saint-Genis Laval, France
2 Observatoire de Paris-Meudon, URA 1757, F-92195 Meudon Principal Cedex, France
3 Université Paris-Sud, F-91405 Orsay, France
Send offprint request to: G. Paturel
Accepted: 5 November 1996
The Lyon-Meudon Extragalactic database (LEDA) gives a free access to the main astrophysical parameters for more than 100 000 galaxies. The most common names are compiled allowing users to recover quickly any galaxy. All these measured astrophysical parameters are first reduced to a common system according to well defined reduction formulae leading to mean homogeneized parameters. Further, these parameters are also transformed into corrected parameters from widely accepted models. For instance, raw 21-cm line widths are transformed into mean standard widths after correction for instrumental effect and then into maximum velocity rotation properly corrected for inclination and non-circular velocity. This paper presents the reduction formulae for each parameter: coordinates, morphological type and luminosity class, diameter and axis ratio, apparent magnitude (UBV, IR, HI) and colors, maximum velocity rotation and central velocity dispersion, radial velocity, mean surface brightness, distance modulus and absolute magnitude, and group membership. For each of these parameters intermediate quantities are given: galactic extinction, inclination, K-correction etc.. All these parameters are available from direct connexion to LEDA and distributed on a standard CD-ROM (PGC-ROM 1996) by the Observatoire de Lyon via the CNRS.
Key words: galaxies: fundamental parameters / astronomical data bases: miscellaneous / catalogs
© European Southern Observatory (ESO), 1997