Caveat: LETG+HRC-S Dispersion Relation
Posted: 12 January 2005
The dispersion relation of the LETG+HRC-S is currently known to approximately a few parts in 10000, across the entire LETG+HRC-S wavelength range. However, due to non-linear imaging distortions of the HRC-S detector, there are residual small-scale dispersion non-linearities that can cause the observed positions of spectral features to be displaced in wavelength relative to their true positions by up to 0.05 Å. This effect is discussed in detail in "The Dispersion Relation of the LETG+HRC-S" memo posted on the LETG instrument page.
corrlam is software written by the LETG calibration team to help correct for the dispersion relation errors. Details on the script are available from the Applying Wavelength Corrections to HRC-S/LETG Data page.