A high-resolution spectrograph for the 72cm Waltz Telescope at Landessternwarte, Heidelberg

The Waltz Spectrograph is a fiber-fed high-resolution échelle spectrograph for the 72 cm Waltz Telescope at the Landessternwarte, Heidelberg. It uses a 31.6 lines/mm 63.5° blaze angle échelle grating in white-pupil configuration, providing a spectral resolving power of R 65,000 covering the spectral range between 450-800nm in one CCD exposure. A prism is used for cross-dispersion of échelle orders. The spectrum is focused by a commercial apochromat onto a 2k×2k CCD detector with 13.5μm per pixel. An exposure meter will be used to obtain precise photon-weighted midpoints of observations, which will be used in the computation of the barycentric corrections of measured radial velocities. A stabilized, newly designed iodine cell is employed for measuring radial velocities with high precision. Our goal is to reach a radial velocity precision of better than 5 m/s, providing an instrument with sufficient precision and sensitivity for the discovery of giant exoplanets. Here we describe the design of the Waltz spectrograph and early on-sky results.