The LETG has significant contributions of higher orders (orders>1)
in the extracted spectrum. These contributions are most noticeable
at large dispersion distances (long wavelengths) and at wavelengths
above 
155 Å can dominate over the first order spectra. This
can be seen in figure XX which plots the effective area of the HRMA +
LETG + HRC-S vs dispersion distance.
Figure 9: LETG Effective Areas