"Modeling the Drift of High-Resolution Spectrographs to Enhance RV Precision"

Abstract

We present a study of the instrumental drift in two high-resolution spectrographs for stellar radial velocity measurements. We use a simple model that allows one to calculate the expected drift from measurements of atmospheric temperature, pressure, and humidity. By comparing the real drift with the model predictions, we can identify and possibly correct instrument instabilities produced by effects other than the atmosphere. This method allows us to improve instrument control and enhance the radial velocity performance of spectrographs that do not include simultaneous wavelength calibration. By applying this method, we measure improvements in radial velocity precision from 30 to 15 m/s.