HARPS secondary guiding

The HARPS spectrograph, after its first six years of operations has established itself as the worldwide reference for accurate Doppler measurements. The radial velocity precision of the instrument on a single measurement is estimated around 60 cm/sec. One of the main limitations to the radial velocity precision is the variation of the injection illumination function due to tracking errors. A light and fast guiding system has been recently developed for HARPS. In this way it is expected to increase the guiding closed loop bandwidth by a factor of 10 with respect to the standard guiding performed with the telescope.