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### A.10.3 Activation Window

Activation Window

The Activation Window allows you to configure an action to perform when a table row is activated by clicking on a row in the Data Window or a point in the Plot Window. It can be obtained by clicking the Activation Action selector at the bottom of the properties panel in the Control Window.

You have various options for how to define the action. On the left of the window is a list of options; you have to choose one of these to determine what kind of action will take place. When you click on one of these options the corresponding controls on the right hand side will become enabled: use these to select the details of the action and then click the OK button so that subsequent activation events will cause the action you have defined (or Cancel so that they won't). When you click OK the Activation Action in the control window will indicate the action you have configured.

The available options are as follows:

No Action
  If this is selected, no special action will take place when a row is activated. This is the default.
Display Cutout Image
  This option presents an easy-to-use way of popping up a cutout image from an image server displaying a region of sky around an activated row. You need to select the columns in your table which represent Right Ascension and Declination, including the units in which they are entered in the table (TOPCAT may be able to guess some or all of this information based on column names, UCDs and unit values, in which case it will enter its guesses in the selectors for you to accept or change). You also need to select the size in pixels of the image you want to see and the name of the survey which will supply the image from one of the listed ones:
  - SuperCOSMOS All-Sky Blue
  - SuperCOSMOS All-Sky Red
  - 2MASS Quick-Look J-band
  - 2MASS Quick-Look H-band
  - 2MASS Quick-Look K-band
  - SDSS Colour Images (note does not provide all-sky coverage)
  When you activate the row, the program will attempt to contact the web server which provides these images, retrieve the image, and display it in an image viewer window. Unfortunately at present the viewer window is an internal one; it does not display in an external SAMP viewer.
View URL as Image
  This option is suitable if one of the columns in your table gives the location (filename or URL) of an image file. The image may be in FITS, GIF, JPEG or PNG format, optionally compressed using gzip, Unix compress, or bzip2 format. Select the column which contains the location, and activating a row will pop up an image viewer to display it (if the table is the result of a single or multiple SIA query, the correct column will probably be filled in automatically). The Image Viewer selector allows you to choose one of the options in Appendix A.10.3.1 or, if you are registered with a SAMP hub, any SAMP image viewer which is also registered - see Section 9.
View URL as Spectrum
  This option is suitable if one of the columns in your table gives the location (filename or URL) of a spectrum file, and you wish to display the spectra in an external SAMP compatible spectrum viewer, such as SPLAT or VOSpec. First select the column which contains the Spectrum Location (if the table is the result of a single or multiple SSA query, the correct column will probably be filled in automatically). Then choose the Spectrum Viewer appropriately. Once this is done, activating a row will try to send the corresponding spectrum to the selected viewer application(s). The details of what data formats are acceptable depend on the viewer application, but FITS, VOTable and some ASCII table variants are usually OK. Note that TOPCAT, as well as a suitable spectrum viewer, must be connected to a running SAMP hub for this to work (see Section 9) - there is no internal spectrum viewer.
View URL as Web Page
  This option is suitable if one of the columns in your table gives the location (filename or URL) of a web page; this should normally be in HTML or plain text, but depending on what browser you use other kinds of document may be supported. Select the column which contains the location and the browser which you would like to use for display, and activating a row will try to pop up a browser window to display it. See Appendix A.10.3.3 for more information about browsers.
Transmit Row
  This option causes the row number of an activated row to be transmitted to one or more other applications using an appropriate SAMP message. This will only work if TOPCAT is registered with a SAMP hub, and so are one or more other applications which understand that message, and the other application(s) know about the table in question, for instance because it has previously been sent to/from TOPCAT. You may specify that either a single application, or all appropriate ones, will receive the messages. See Section 9 for more explanation.
Transmit Coordinates
  This option causes the sky position of an activated row to be transmitted to one or more other applications using an appropriate SAMP message. This will only work if TOPCAT is registered with a SAMP hub, and so are one or more other applications which understand that message. An example might be a sky viewing application such as Aladin which can point to a particular region of sky whenever you activate a point. You need to specify the columns which represent (J2000) Right Ascension and Declination, and optionally a particular listener to receive the messages (otherwise all registered ones will). See Section 9 for more explanation.
Execute Custom Code
  This option must be used if none of the others (which are fairly restrictive) do what you want. It is highly flexible, but not so easy to use. What you have to do is to write an expression following the rules in Section 7 involving some of the column names which will be invoked when a row is activated. This expression will typically have the effect of popping up an image or a spectrum in a viewer, but, especially if you link in your own functions (see Section 7.9) it can do pretty much anything.

  Functions which are expected to be useful for activation actions are described in Appendix B.2 and include some general-purpose ones (`displayImage` and `displaySpectrum` to display an image or spectrum in an external viewer) as well as a few which are relevant to particular survey data, for instance the `spectra2QZ()` function, which will pop up a spectrum viewer displaying all the spectra related to a given row of 2QZ survey data based on the contents of its NAME column.

As the above list shows, most of the activation actions you can define result in a viewer window of some kind popping up. Exactly what kind of viewer is used depends on how TOPCAT is set up and in some cases on your choices. More details of the viewer programs available are given in the following subsections. If these don't do what you want, you can use the Execute Custom Code option, perhaps in conjunction with user-defined functions or the `System` `exec()` functions described in Appendix B.2, to invoke your own.

- A.10.3.1 Image Viewer Applications
- A.10.3.2 Spectrum Viewers
- A.10.3.3 Web Browsers

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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@jiscmail.ac.uk