The GMT telescope metrology system design

The Giant Magellan Telescope will be a 25.4-m visible and infrared telescope at Las Campanas Observatory. The optical design consists of 7 8.4-m primary mirror segments that reflect light to 7 secondary mirror segments in a doubly segmented direct Gregorian configuration. GMT is developing a Telescope Metrology System (TMS) to decrease the complexity of alignment and increase observatory efficiency. The TMS has been developed to Preliminary Design Review level. A prototyping, modelling, and analysis effort has been completed. All components of the system were matured, and the edge-sensing strategy was significantly revised. This paper describes the current TMS design.