In a few cases the responsivity drift correction does not work very well. This is particularly true for L02 and L04 AOTs, where the drift correction is more sensitive to the effect of glitches, leading to faint lines no longer being visible after the correction has been applied. It is recommended that you compare the data in the LSAN file with the data in the LSNR file, which do not have the absolute responsivity correction or the responsivity drift correction applied. If required, the absolute responsivity correction can be applied to the LSNR data, as described in the `Post processing' chapter.