The Catalogs Menu

The VTT can plot astronomical object information from a variety of catalogs on top of an image. Once catalog information has been retrieved, the catalog objects can be filtered based on object type and magnitude, and the Identify Tool can be used to see details about a particular catalog object.

Web Query

This allows you to query on-line information services about the current image or target. The results of the query are then displayed in a separate browser window.

Catalog Overlay Options

The Catalog Overlay Options window contains three tabs which allow you to choose search catalogs, filter the results, and set display options.

Catalogs Tab:

Display Selected Catalogs: This check box allows you to turn the catalog overlay feature on and off. It performs the same function as the " Catalog" button in the top tool bar. When you turn it on, the Visual Target Tuner will attempt to connect to the selected catalogs and perform a search. Once a search is complete, the results are displayed in the image area. (To stop a search that is taking too long, click on the orbiting icon in the upper left corner. Click on a task and click "Stop Task".)

Available catalogs: The list of available catalogs supported by the Visual Target Tuner appear as check boxes below "Display Selected Catalogs". Catalogs that will be searched are marked with a check. Simply click on the check box next to a catalog to toggle that catalog on or off. Search results from multiple catalogs will be displayed together.

Tabs for parameters to limit searches: Those catalogs which support additional search parameters will have a tab with the catalog name attached. Select the tab to display the additional search parameters for that catalog. Most catalogs support specifying a search radius. The default is to use the size of the image. Due to the number of objects in the GSC2 the magnitude range defaults for this catalog have been set to return objects in the range 0.0 to 15.0. If fainter objects are desired then the user should also reduce the search radius. (Note that you need to toggle "Display Selected Catalog" off and on to force a revised search.)

Filter Tab:

Filter by V-magnitude: This option allows you to filter the displayed objects by their magnitude. The minimum and maximum V-magnitudes of objects to be displayed are set by entering values in the range fields. By default, all objects are displayed regardless of magnitude. To turn on the magnitude filter, click the check box. Note that some objects in some catalogs do not have associated magnitude information, so they will automatically disappear when the magnitude filter is turned on.

Filter for possible Guide Stars: This option implements a subset of the Guide Star Selection rules for HST. This option is designed to provide the user with an indication of whether or not the selected observation will incur problems during the guide star selection phase of observation scheduling. Turning this option on will display the HST FOV, the GSC overlay, and will filter GSC entries so that only potential guide stars are displayed. If there are two FGS pickles with at least one GSC entry displayed in each, then potential guide star pair(s) for this observation exist. The circular regions in the corner of each FGS are avoidance areas. GSC entries in these areas are not usable as guide stars. The presence of GSC entries in the pickles (as described above) is an indication that suitable guide stars may be available. The absence of GSC entries in any of the pickles is an indication that the observation will fail to schedule for lack of guide stars.

Filter by Object Type: This table contains all object types displayed from the catalogs searched. By default, all types are checked, indicating that all types are to be displayed. To turn off display of a particular object type, uncheck that item in this table. All labels for objects of that type will then disappear from the display area.

Display Tab:

Label Style: By default, object names are displayed next to the object in the Visual Target Tuner display area. But the label can be changed to magnitude, object type, or to no label at all.

Show Position Uncertainty: This option displays the uncertainty of each object's position as an ellipse around the object. Note that some databases do not give position uncertainty information, in which case this option will have no effect.

Catalog Table View

The Catalog Table View shows a table containing entries for each catalog object displayed on the current image. The Name, RA, DEC, and flux information are included. Selecting an entry in the table will highlight the corresponding object on the image in the selected color. The Save button allows the contents of the table to be saved as a comma separated value (CSV) format file suitable for importing into APT as a target list.

Import Catalog Objects

Import Catalog Objects provides the capability to read and display a user supplied list of catalog objects. The format of the input file is identical to that created via the Save function under Catalog Table View. The minimum data required on import are Target#, Name, RA, Dec.