Comparison of the central 5″ spectrum extracted from the V500 (black, thick solid line) and V1200 (red, dashed line) grating datacubes for three typical objects (from left to right): NGC 6411, the brightest object observed so far; NGC 6497, a spiral galaxy with an average brightness, and UGC 11262, the faintest target observed so far. The green thin solid line shows the difference between both spectra. The orange hashed region indicate the  ± 10% median intensity range of both spectra around the zero level, indicated with a grey continuous line.