I want to do a spectral map – how come the slits are not exactly on the same place?
The spectral map positions are in array coordinates, which are created by moving parallel and perpendicular to the slit in each case. Because the slits are not exactly parallel (or perpendicular) to each other, the map positions are not exactly in the same places either. The best way to illustrate this is to overlay SL and SH — these modules are nearly 45 degrees with respect to each other, so the map positions are not at all the same.
