The Work on Cross-Reference Tables
A large fraction of open clusters have been studied by several authors who
have created personal numbering systems. The intersections between these
different studies are often partial because photometric studies
go to fainter magnitudes in smaller areas, while proper motion studies are
concernerd with stars of brighter limiting magnitudes, but over a much wider field.
This situation creates a serious problem to work efficiently with star cluster
observations, because one usually needs to know the various numbers attributed
to each star in a cluster. This is also a major concern for the development
of the database.
Since 1972, a big effort has been undertaken to provide a solution to this
problem. A convenient numbering system has been adopted for each
cluster and cross-identifications between numbering systems in many
clusters have been determined. These cross-identifications have been stored
in tables (Mermilliod J.-C. 1979, A&AS 36, 163). Their
structure should be obvious: the first column contains the adopted
numbering system, and the subsequent columns contain the corresponding
numbers attributed by the various authors.
As general rule, the adopted numbering system is similar to the one given
in the first reference. It has often been extended to include additional
stars coming from the other studies.
Access to the tables
The present Web page offers a possibility to display the existing tables
and search them directly for specific star numbers in any of the listed
The sort on columns labelled 13 or 14 does presently not work when the numbering
system is complex, like 22 - 75.
Look at the help page to see how to use it.