Gemini high-resolution optical spectrograph (GHOST) outer enclosure design and construction

The Gemini High-Resolution Optical SpecTrograph (GHOST) is the newest instrument being integrated for the Gemini telescopes, in a collaboration between the Australian National University (ANU), the NRC-Herzberg in Canada and the Australian Astronomical Observatory (AAO). The GHOST outer enclosure consists of 20 heated thermal panels, forming an encompassing structure with a stationary 'bridge' assembly and two removable sections for access. The outer enclosure provides an ultra-stable, dark environment for the bench spectrograph. This paper reviews the outer enclosure construction from a practical standpoint, examining how environmental requirements are met through the thermal panel construction, light seal and dry air system designs. This paper also describes thermal panel production workflow, enclosure assembly methodology, alignment and cable routing challenges. Results of the enclosure's thermal stability verification tests are presented and a list of lessons learned.