empirical template RVs

As my loyal reader knows, I am finishing up an old paper on information theory, radial velocities, and measurement. Today I wrote the code that produces radial-velocity measurements using cross-correlations with an empirical template that is built from the data themselves. I learned a lot doing this! One thing I learned is that edge effects matter: It is important to either design your template, or else design your method, such that as you redshift or blueshift the template, lines that enter or leave the spectral range don't mess up your radial-velocity measurements. In principle this is all handled correctly by correct statistics, but in practice it requires attention!