<title>Development of a star tracker for the Hobby-Eberly Telescope</title>

Abstract

A large prime-focus robotic star tracking device has been designed and constructed and is now undergoing commissioning atop the 9.2-meter Hobby-Eberly Telescope at McDonald Observatory in West Texas. The novel, cost-effective tracker represents a major departure in the way very large astronomical telescopes are controlled in pointing, tracking, and guiding. The tracker development and design implementation included detailed structural analysis, the application of minimum constraint kinematic design to a large gantry-type motion control system, and the unique application of a large precision hexapod to solve the dynamic tilting and focus motion problems. Challenging fabrication, test, and on-telescope assembly problems were overcome. Performance data of the completed device demonstrate that the tracker design and implementation efforts were successful.