Wavelength and temporal dependence of the observed RV. Top: standard deviation S_dev (black line) and formal error on RV measurements (red line) for each order from our processing, averaged over the first 100 exposures only. The ratio between the two quantities is shown in violet. Bottom: same as top but for the last 100 exposures. We note the high ratio found in the blue orders during the second half of the observational time, a sign of spurious jitter due to a blue cryostat thermal instability.