Using the Plot/Image Interface with Aladin

If you have an image with an associated source catalog, you can use Aladin to make a plot (e.g. a color-color plot). You can then mark points in the plot and have them highlighted in the image (and vice versa). For a demonstration using a specific example, see the training movie.

You first need to read in your image and source catalog. With the catalog selected in the Aladin Tree, go under Catalog and select "Create a Scatter Plot".

Select the appropriate columns for the plot. Note that you can flip the axis (i.e. go from Minimum to Maximum instead of Maximum to Minimum) if necessary.

If you click on a star in the plot (or image), it will be highlighted in the image (or plot). You can also selected a group of stars in the plot, and these will be highlighted in the image.

If you select the catalog in the Aladin Tree, you can change the scaling of the plot by using the Zoom function (just like with images).

You can also add new columns to your catalog (based on data in the catalog). Under Catalog, select "Add a New Column". Enter the name of the column, and create the new field.

You can now use this column to make a new plot.

This is the initial release of this capability, and there are some limitations in its use

  • if you have extreme points (i.e. points far from the main body of the data), the initial scaling can sometimes miss those points (you can Zoom out to see the points)
  • the default scaling can be less than optimal (e.g. as in the example above, there are no tick marks along the y-axis)
  • you can't manually set the scaling
  • if you don't have the Aladin spreadsheet open (the default is for it to be closed), then when you select objects it will open automatically. This could change the scaling in the plots such that the objects you selected are now out of the plot area displayed.

    We welcome any suggestions for improvements or enhancements, which we will pass them on to the Aladin team for consideration.

    Last modified: June 4, 2014.