The performance of the new Fabry-Perot calibration system of the radial velocity spectrograph HARPS

The Observatory of Geneva has designed, built and tested in collaboration with ESO a calibrator system based on a Fabry-Perot (FP) interferometer to explore its potential in the calibration of radial velocity (RV) spectrographs. Today, the RV technique has pushed the planet detection limits down to super-earths but the reach the precision required to detect earth-like planets it is necessary to reach a precision around 1cm s⁻¹. While a significant part of the error budget is the incompressible photon noise, another part is the noise in the wavelength calibration of the spectrograph. It is to address this problem that we have developed this new device. We have obtained exciting results with the calibrator system demonstrated 10 cm s⁻¹ stability over one night and 1 m s⁻¹ over 60 days. By further improving the injection system we are aiming at a 1 m s⁻¹ repeatability over the long term.