Data Reduction Frequently Asked Questions
I found that I obtain very different RV values for different spectral templates/masks of the order of several hundred m/s. Is this normal?
This is normal. The instrumental offset is of this order of magnitude. The RV calculation is a precise -- not accurate -- measurement and as such comparing the absolute results with different masks does not make physical sense. A mask comparison should not be confused with a measurement of the accuracy of ESPRESSO (it is not).