Compilation of Group membership

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This compilation gives the membership of object to an association. An assosiation is defined as a group or cluster of galaxies, or more generally as a collection of objects associated through some of their attributes. For example, this concept allows to link HII regions, or supernovae to their host or parent galaxy: In this case, the association is the parent galaxy and the members are the HI regions or the supernovae. Some groups indexed in Leda do not have the list of their members stored in the group catalog.

Description of the fields

Below is a description of the fields of the table that can be accessed through the interfaces.

Field: g_id

pgc number of the group. The pgc number indexes all the objects of the database and is sometime associated with the PGC name, it is intended for internal usage and should not be used to name objects in publications.

Field: group

Designation of the association

The following group catalogues are in HyperLeda:

1000	Nilson P.; 1973, Uppsala General Catalogue of Galaxies, Uppsala Astr. Obs. Annaler, Band 6 (membership defined from a visual estimation based on position and aspect)
30001	Tully R.B.; 1988, Nearby Galaxies Catalog, Cambridge University Press (membership defined from a hierarchical method)
30002	Huchra J.P., Geller M.J.; 1982, Astrophys. J., 257, 423 (membership defined from a percolation method)
30003	Ramella M., Geller M.J., Huchra J.; 1989, Astrophys. J., 344, 57 (membership defined from a percolation method)
30004	Garcia A.M.; 1993, Astron. Astrophys. Suppl. Ser., 100, 47 (membership defined from a method combining percolation and hierarchical algorithms)

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Questions: prugniel@obs.univ-lyon1.fr