Megan Bedell showed me results this week that the velocity measured for a star by HARPS appears to be correlated with the pipeline-determined wavelength solution parameters. That's bad! But also good! Because it may give us way to improve the end-to-end calibration of radial velocities. We started down the path of looking at train-and-test regression, where we fit the relationship in all but a held-out exposure, and apply the relationship to the held-out exposure in a (gasp!) data-correction step. Or something along those lines to avoid over-fitting. Of course the right thing to do might be to fit everything at once, including the radial-velocity curve generated by exoplanets, but I don't think the exoplaneteers would like that so much.