2. Define the continuum by taking the blue line and placing it near the spectral line. The changing blue rectangle is the equivalent width given that continuum. Its reported in the box below the applet in units of angstroms.

3. This is an A star spectrum; more spectra will be added later -this is still in development.

4. Change the horizontal scale by typing in wavelength limits in the two boxes.

5. The yellow lines define the Reinmann sums in which the integration of the line shape is done.

more later