Telluric correction for quasar SDSS1431+0535 where brown is the uncorrected spectrum and purple is the corrected spectrum and teal is the corrected spectrum smoothed by 50 pixels. The regions of pure noise are where the atmospheric transmission is ~zero, thus only leaving noise after correction. Residuals after correction are visible. The noise image is corrected correspondingly and regions severely affected are down-weighted in the weighted combination.