Comparison of the central 5″ spectrum extracted from the V500 (thick back solid-line) grating datacubes with the corresponding spectrum obtained by the SDSS (thick red dashed-line), and the difference between both spectra (thin green solid-line). There are the only three galaxies in the presented sample with SDSS spectra: NGC 6394, UGC 09892 and UGC 11649 (from left to right).