WIYN Telescope: vibration analysis and mitigation strategies

The NEID extreme precision radial velocity spectrometer is in operation at the WIYN 3.5-meter telescope located at the Kitt Peak National Observatory, Tucson, Arizona. This newly-commissioned instrument serves both the national exoplanet research community as well as the WIYN consortium partners. In order to meet the stringent 27 cm per second radial velocity precision^[1], and in particular to maximize the efficiency of the 5-year radial velocity survey, it is critical to understand the WIYN telescope vibration environment. In this presentation, we describe the vibration measurement techniques and results used for quantifying the vibration of: the telescope ancillary equipment, the telescope mount, the telescope primary mirror cooling systems, the telescope instruments, wind, and other sources and their effect on the telescope image. Additionally, mitigation methods, current and planned are discussed. This work continues on from a previous paper at this conference^[2], where we presented data gathered from accelerometers on WIYN to begin identifying major features in the vibration spectra and simulate the input to the tip-tilt correction system for the NEID fiber-feed. The WIYN telescope has a well-ventilated and compact dome that ensures excellent seeing, but is also prone to wind-shake. For wind-related vibrations in particular, it is important to model the structural modes to design mitigation strategies and here we discuss possible experimental methods and data analysis techniques to address this. This work will be relevant to upgrade and retrofit efforts as older observatories incorporate low-order wavefront correction to stabilize light to advanced spectrometers and imagers. See Li et al. (this conference).