Interoperability between Astro-WISE and Virtual Observatory software

In this tutorial we will use SAMP connectivity to find bright blue galaxies in a specific WFI field in a graphical, interactive way. You will need to have javaws (java webstart) installed on your system.


SAMP (Simple Application Messaging Protocol) is a communication protocol for astronomical tools. Several pieces of software have SAMP support, we will use TOPCAT (a table viewer) and Aladin (an image viewer).

  1. Select one of your own SourceLists, or use SourceList with SLID 135591 (from a WFI V band image.) We will assume the SourceList is called sl.

    awe> sl = (SourceList.SLID == 135591)[0]
  2. Starting other SAMP applications.
    Start the following programs:
    • Aladin (this will start a SAMP HUB)
    • TOPCAT

    The TOPCAT main window. The buttons used is this tutorial are circled. From top to bottom, from left to right: the ‘Interop’ menu, the ‘Row Subset’ button, the ‘Scatter Plot’ button and the ‘Activation Action’ button.

    Starting these programs requires java, people in Leiden can try the computer para1 if there is no (or an incorrect) java version installed on their machine. TOPCAT can be started from the terminal by typing
    awe> os.system('topcat &')

    Alternatively you could use javaws (if available) to start both TOPCAT and Aladin.

    awe> os.system('javaws &')
    awe> os.system('javaws &')
  3. Connect Astro-WISE to the hub and transmit your SourceList (and its frame) through SAMP.

    awe> from import Samp
    awe> samp = Samp()
    awe> samp.broadcast(sl.frame)
    awe> samp.broadcast(sl)
  4. Select some sources in TOPCAT and send their SIDs to the awe-prompt. You should see your SourceList loaded in the TOPCAT ‘Table List’ in its main window. Use TOPCAT to select specific sources of your interest and send their SIDs to the awe-prompt.
    Solution A (‘highlight’ sources):
    • In the main TOPCAT window, press the (empty) button next to ‘Activation Action’ and choose ‘Transmit Row’ from the ‘Set Activation Action’ window that pops up, and close it.

    • Create a ‘Scatter Plot’ and display your favorite attributes.

    • Click on an interesting source in the plot.

    • Retrieve the SID in the awe-prompt with

      awe> samp.highlighted(sl)

    Solution B (‘select’ sources):

    • From the main TOPCAT window create a ‘Scatter Plot’ and display your favorite attributes.

    • Use the ‘select region’ tool to select multiple interesting sources at once.

    • Click the ‘select region’ button again to create a subset containing the sources (you need to name the subset).

    • Open the ‘Row Subsets’ window by clicking its button in the main TOPCAT window.

    • On the ‘Row Subsets’ window, select your subset and press the ‘broadcast subset’ button.

    • Retrieve the SIDs in the awe-prompt with

      awe> samp.selected(sl)
      [0, 2, 820, 983, 1037, 1090, 1093, 1139, 1175, 1197, 1292, 1392]

      The TOPCAT Scatter Plot window. In blue the ‘Select Region’ button has been circled. With this tool the blue points have been selected and labeled ‘interesting’ (Solution B). One of the points is selected with the black cross hair and send over SAMP (Solution A)


      The TOPCAT Row Subset window. The ‘Transmit Subset’ button is encircled, it is grayed out when no subset is selected yet.