Querying Vizier From Xamin

The Vizier system hosted at the CDS is an unmatched source for astronomical tables with nearly 10,000 resources and over 20,000 tables. All public Vizier tables are queryable through Xamin.

 

First you have to select a table (or tables).

If you know the designation of the Vizier table you can just enter it directly. E.g., the USNO B catalog is catalog I/284 and you can just type that name in the ‘Enter table name’ box of the Tables Explorer. For the first couple of characters as you type, you may see a menu of HEASARC tables that start with the same letters. You can just ignore these.

Selecting tables with direct entry

Entering a Vizier table name directly

Hit return after you’ve entered the table name.

Or you can use the Available tables tree. All Vizier tables are listed within the External tables tree. We open the External tables. Vizier tables are the first entry. If we open this up we get the nine Vizier catalog type categories, with Roman numeral prefixes I through IX, mirrored catalogs, B, and many catalogs associated with specific journals. These have a prefix the starts with J and includes a contraction of the journal name, e.g., J/ApJ for Astrophysical Journal. We can open up any of these. If there are more than 50 resources included for that category, then these resources are broken up into subcategories in the appropriate order (e.g., the resource number for the numbered tables, or by journal volume for journal tables) into groups of 25. If we need to, we open up this level of the tree to see the actual Vizier resources.

Some resources include multiple tables so that they are still branch nodes in the table tree. They can be opened up to get the individual tables for the resource. Other Vizier resources have only a single table, so the resource is a leaf node.

Selecting tables with direct entry

Selecting a Vizier table using the Tables tree

 

Once you see the table you want you can double click it, click on the + icon or drag it into the selected tables area to select it.

If you know a bit about what you are looking for, or have some specific information like a bibcode, it may be more efficient to enter that in the Table Explorers, Search by Keywords box. That will look for matching Vizier entries, and you can select the table from the pane that come up when you click on the nearby Search button.

Selecting tables with direct entry Finding a Vizier table using the keyword search]

 

Just click on the + icon to select a table from the list of returned tables.

You can use all three of these mechanisms to select Vizier tables in the Tables Explorer. If you want to get documentation on a Vizier table, you can click on the resource name in either the Available or Selected tables trees. The documentation shows at the bottom of the query pane. You may want to enlarge that part by dragging the divider up to view the document.

Once you’ve selected the table you can, in principle, do any kind of query. However only positional constraints and relatively simple constraints on columns can be handled by Vizier itself. If you want to specify complex constraints or a cross-correlation, Xamin may try to download the table and use a local copy. For many Vizier tables with a few hundred of thousand rows, that will work fine, but Vizier has many very large tables and so a naive query may time out.

 

Let us know if you have any questions regarding Vizier queries in Xamin.

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