SOPHIE gets Fabry-Pérot calibration unit

Raw CCD image of the spectrum of a K0V star showing the simultaneous Fabry-Pérot spectrum

Starting in the Spring of 2017 a Fabry-Pérot étalon, illuminated by a supercontinuum laser source, was installed in the new Calibration Unit located in the temperature-controlled room downstairs where ELODIE used to be. This lamp is now used for all observations needing very accurate radial velocities (simultaneous FP). The Thorium lamps are used sparingly, only to determine the wavelength calibration zero point at the beginning of the night or occasionally to check it. The richness of the FP spectrum is a definite advantange compared to the irregular distribution of the Th-Ar emission lines.