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#### A.8.1.2 Single Positional Search Panel

Single Positional Search Panel

The Single Positional Search Panel appears in VO-based table load dialogues and is used to specify data queries on a single region of the sky. The purpose is to load a new table (containing entries representing catalogue entries, images or spectra). To use it you must fill in the URL field and the position definition, and then hit the OK button.

URL
  This must contain the service URL for the data service that you are querying. Usually, this will be filled in by selecting one of the services obtained by the registry query. However, you can fill it in manually with the URL of a service you know about if you prefer. If you know what you're doing, it's also possible to doctor a service URL filled in by the registry selection, for instance by adding `&name=value` parameters to it.
Object Name
  You can fill this in with the name of an object to be resolved by SIMBAD, and hit the Resolve button, which will fill in the coordinates in the RA and Dec fields below. If you enter the RA and Dec manually, you don't need to use this field.
RA and Dec
  Fill in the central position in terms of J2000 Right Ascension and Declination that you are interested in here. You can either do it manually, or by using the Object Name field as above. Select the units as appropriate.
Radius
  Indicates how large is the region you are interested in. This field has slightly different appearance and meaning for the different data service types; hover over it with the mouse to see a tooltip with the details. For SIA and SSA, but not for Cone Search, it is permissible to leave it blank (though certain services don't seem to like that). Select the units as appropriate.

When the fields are filled in, hit the OK button and wait for the new table defined by your query parameters to load. If you get bored waiting (the service may be down, or just very slow, or you may have submitted a query with a very large return set), you can hit the Cancel button, and perhaps adjust the parameters and try again.

If a SAMP hub is running (see Section 9), then other running clients may be able to fill in the RA and Dec coordinates. For instance clicking on a sky position in an image viewing tool might fill in the sky position you clicked on. Usually this will happen automatically. This is often convenient, but may not be what you want. You can control whether incoming coordinate settings are accepted in this way using the Accept Sky Positions toggle below the Resolve button, or using the corresponding item in the Interop menu.

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TOPCAT - Tool for OPerations on Catalogues And Tables
Starlink User Note253
TOPCAT web page: http://www.starlink.ac.uk/topcat/
Author email: m.b.taylor@bristol.ac.uk
Mailing list: topcat-user@bristol.ac.uk