New Hobby Eberly telescope metrology systems: design, implementation, and on-sky performance

The Hobby-Eberly Telescope is an innovative 10-meter telescope, located at the McDonald Observatory. We have completed a major multi-year upgrade of the HET that has substantially increased the field of view to 22 arcminutes by replacing the optical corrector, tracker, and prime focus instrument package and by developing a new telescope control and metrology systems. The metrology systems include four independent optical sensors to provide fully redundant alignment and pointing information to keep the telescope aligned to within a few microns and a few arc seconds. We detail the design, implementation, on-sky performance, and lessons learned.