The Lyon-Meudon Extragalactic Database (LEDA) was created in 1983 at Lyon Observatory and is the oldest extragalactic database (Paturel et al. 1988; Paturel, Gouguenheim, and Bottinelli 1992). It gives access to many parameters (up to 66 per object) of astrophysical interest for about 97,000 galaxies, as of June 1994. Finder charts with SAO stars can be created and images taken from the POSS are available for about 58,000 galaxies in Postscript format. An X-Windows interface allows users to display these on their screen. The main idea is to collect raw measurements from literature and to calculate mean homogenized data in the same spirit of de Vaucouleurs et al. when preparing the series of Reference Catalogs of Galaxies (RC1, RC2, RC3). In fact, the RC3 (de Vaucouleurs et al. 1991) and the Principle Galaxy Catalog (PGC, Paturel et al. 1989; Paturel, Bottinelli, and Gouguenheim 1993) were created using LEDA.
An SQL-like query language allows the user to define and extract galaxy samples by complex criteria. Finder charts in Postscript format can be created with LEDA galaxies and SAO stars of any user-specified position at almost any scale (including that of the POSS and ESO/SERC sky surveys). A batch mode allows queries via e-mail by sending a list of names or coordinates to ledamail@lmc.univ-lyon1.fr. Depending on whether the subject specified is LIST or LISTALL, the system will return (via e-mail) either the basic or all stored astrophysical parameters of the retrieved objects. For subjects FLAMEQ, FLAMGA, and FLAMSG the system will return Flamsteed all-sky projections in Postscript format for any set of input objects (or positions in RA and DEC of B1950).
LEDA is accessible via telnet to lmc.univ-lyon1.fr (134.214.4.7), login as leda. No password is required. The novice user may choose the menu option Instructions for Use. New facilities are frequently added to the system. Suggestions and questions should be sent to G. Paturel (patu@adel.univ-lyon1.fr) or M.-C. Marthinet (mc@lmc.univ-lyon1.fr).