Derippling

When observations are interleaved (see Interleave and Coadd ), variations in throughput, sky brightness, and other factors may cause flux levels to change between the interleaved exposures, resulting in a ripple in the interleaved spectrum. This ripple is removed by creating a ripple flat with a ripple that has the same frequency as the interleaving, i.e. if 2x2 interleaving is performed, a ripple flat with a frequency of two pixels is created. This ripple flat is divided into the extracted spectrum unless the ripple amplitude is less than 70
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