Evolution of the S/N of the retrieved H₂O injected signal with increasing SYSREM iterations. The model was injected at three times the expected level of absorption. The star symbols mark the iteration in which the recovery of the injected signal is maximized. The injected signal would not be recovered with confidence if its peak S/N was below 3 (shaded region). Spectral order 15 (in gray) was excluded from the analysis due to the presence of residuals in the final cross-correlation results.