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Acquisition and guiding unit for Gemini 8-m telescopes: a progress report

An international partnership of the USA, UK, Canada, Chile, Argentina and Brazil are projecting two high performance 8- meter Aperture Optical/Infrared Telescopes to be commissioned between the years 1998 and 2000 at Mauna Kea, Hawaii, and Cerro Pachon, Chile. The aim is to exploit the best natural observing conditions to undertake a broad range of astronomical research programs within the national communities of other countries. Zeiss was awarded two mayor contracts within this project, to design, manufacture and test the secondary mirrors and the Gemini Acquisition and Guiding system (GAG) for the 8m telescopes. The current paper refers to the GAG. The Gemini Acquisition and Guiding Unit are complex integrated systems, including optics, mechanical assemblies, detectors and control and signal processing software. The project is to be accomplished under subcontract and in cooperation with the Royal Greenwich Observatory in the United Kingdom. We briefly review the technological and astronomical background of the project and the technical specification of the GAG. The paper describes the design of the Acquisition and Guidance Unit, highlights some design criteria and discusses the expected performance. A report about the actual status of work is given.