Virtual Observatory

The SAI OCL Catalog site provides several VO-enabled modes of operation:

  • VO-enabled catalog data analysis from a browser
  • Simple ConeSearch Service for programmatic access (positional queries).
    Endpoint URL is
  • Catalog exported in VOTable format [link]

Below come several simple examples of what can be achieved with these VO resources. Be sure you have Java installed on your workstation.

Useful recipes

  • VO-enabled catalog analysis from a browser
    1. Presently, this recipe works with Firefox (Windows, MacOS, Linux), Internet Explorer (Windows) and Opera (Windows) browsers with Java plugin 1.6 installed. Click on "VO mode: turn on" link in the VO menu at the top right corner of your browser screen. Then press "Open" and "OK" in every window raising, it is safe. Small (500KB) applet will be loaded into your browser and will check if there are necessary VO applications (Aladin and TOPCAT) running on your system. You can start them manually beforehand, but be sure they are running in SAMP mode. Otherwise the applet will offer you to launch TOPCAT: be patient, it is 12MB download. When it is over, the green icon will appear in the VO menu at the top right: the system is ready. You may want to launch Aladin as well. For that purpose click on the "start" link in the VO menu just below the Aladin item. Now you are able to conveniently interact with VO applications through a web browser.
    2. Go to Catalog page. In a moment the catalog will be loaded automatically in all running VO tools. The table displayed in a browser window will somewhat change in VO mode as well: there are checkboxes appeared on the left of every row, RA-Dec coordinates became clickable, and by moving mouse over the table rows you can now highlight them.
    3. By clicking on underscored coordinates in a cluster list Aladin will automatically load DSS2 cluster image, overplotting UCAC3 objects within cluster's radius. Note that highlighted (by mouse movement or by ticking checkboxes) rows are also highlighted in VO tools.
    4. Don't forget you can sort table in a browser by clicking on a column headers.
    5. Go to some cluster page by clicking on its name. Locate the data available for this cluster at the bottom of the page (typically, (J, J-H) isochrone and 2MASS data are available; sometimes there is photometric dataset, check Structure of Data page for a list of clusters with deep photometry). If you move the mouse over some link, the "Broadcast" button will appear just next to it. Click on the button to send the data to VO applications.
  • TOPCAT usage example
    1. Start TOPCAT (just press "Open" and "OK" in every window raising, it is secure). Main TOPCAT window with SAI OCL catalog loaded will appear.
    2. Press "Activation action: no action" button in the main window, then choose either: (1) Display Cutout Image → SuperCOSMOS All-Sky Red → Width/height 500 pixels; or (2) View URL as Image → set Image Location Column to cluster_hess_diagram_file_url or cluster_cmd_file_url → Image Format: PNG. Then press "OK" button in the bottom of the window.
    3. Click on the button "Display table cell data" and/or "Spherical polar scatter plot", etc. on the toolbar to examine the data. Once you select a row or some point, a window with some additional plot or image (depending on what you have chosen at previous step) will appear.