For this example we will work with the Fe line seen at 15A. First lets enlarge the region near the line.
isis> xrange(14.99,15.07);
isis> plot_data(10);
and now we see the data as plotted in figure 2.
Figure: The 15 Å Fe line in the Capella spectrum with
the fitted lsf shown in red.
Figure: The 15 Å Fe line in the Capella spectrum