Masters-out of each night divided by the highest signal-to-noise master-out from their epoch (Nights 4 and 7, respectively), zoomed on each line core of the Na D doublet. This shows the discrepancy between each night master within their respective epoch compared to the noise level. The center of each line is represented by a dashed vertical blue line. Top: night masters residuals of Epoch 2. Bottom: night masters residuals of Epoch 3. Left: Na D2 line zoom. Right: Na D1 line zoom.