slit_function_file fileThe file must contain two columns. Column 1 is the wavelength, in nm, and relative to the center wavelength. Column 2 is the corresponding slit function value. It must be unity at the maximum. The wavelength steps in the slit function file must be equidistant. Comments start with #. Empty lines are ignored. Please note that prior to convolution the spectrum is interpolated to the wavelength steps of the slit function. For this reason, make sure that the resolution of the slit function is high enough even if the slit function is e.g. a simple triangle which could in principle be described with 3 grid points. For an example see examples/TRI_SLIT.DAT and the make_slitfunction tool.