It is sometimes useful to have a list of those clusters which have many stars observed in one kind of data, or to know which clusters lack data. The command slm allows this kind of queries. The bda directory contains a sub-directory contenu which collects files (one per data type) containing the name of the cluster, the number of stars and the number of measurements available. The selection is made only on the number of stars. This command may be run from anywhere in the database. It always needs at least one argument, i.e. the data type.
> slm ubv lists the whole file.
> slm ubv -gt 200 select the clusters having more than 200 stars observed in UBV.
> slm gpo list the file containing the information on radial velocities from objective prism spectra.
> slm map list the cluster for which a scanned map is available
> slm ubv -histo display the UBV database content in a histogram.
> slm ubv 2287 display the information for NGC 2287.
It is also possible to answer the question: "Which are the clusters that have at the same time red giants and DDO data" with the option -int and the indication of both datatypes.
> slm gk -int ddo list cluster with red giants and DDO data
> slm gk -int ddo ngc restrict the output to NGC clusters
One can refine the intersection by setting a condition to the first datatype, by asking, for example that te number of red giants must be larger than ten.
> slm -gt 10 gk -int ddo list cluster with at least 10 red giants and DDO data. No selection is made on the DDO data
> slm -gt 10 gk -int ddo ngc restrict the output to NGC clusters
Finally, constraints can be placed on both selections to avoid selecting clusters with many data in one datatype and few in the second one.
> slm -gt 10 gk -int ddo -gt 10 list cluster with at least 10 red giants and DDO data for at least 10 stars.