Parameter exploration made with our slit filtering tool. The position angle of the slit was varied from 0° to 175° in steps of 10°. The offset values are –020, –015, –010, –006, –003, 0′′, 010, and 020. The slit position angle is varied when moving horizontally in the figure (the PA values are printed at the top) and the offset is varied when moving vertically in the figure (the offset values are printed on the left). The y values are normalized fluxes from –0.1 to 1.7, while the x values are velocities from –15 km s^-1 to +15 km s^-1.