It detects if ellipse has failed by checking if the resulting data file exists. It adds a column (validellipse) that contains 1 if ellipse didn't fail and 0 if ellipse failed. It returns a votable that contains all the data with the new column and a votable that contains only the rows where ellipse didn't failed. It uses astrotaverna plugin (http://wf4ever.github.com/astrotaverna/).