MSE observatory: a revised and optimized astronomical facility

The Canada-France-Hawaii- TelescopeCorporation (CFHT) plans to repurposeits observatoryon the summitof Maunakea and operate a (60 segment) 11.25m aperture wide field spectroscopic survey telescope, the Maunakea Spectroscopic Explorer (MSE). The prime focus telescopewill be equipped with dedicated instrumentation to take advantage of one of the best sites in the northern hemisphere and offer its users the ability to perform large surveys. Central themes of the development plan are reusing and upgrading wherever possible. MSE will reuse the CFHT site and build upon the existing observatoryinfrastructure, using the same building and telescopepier as CFHT, while minimizing environmental impact on the summit. MSE will require structural support upgrades to the building to meet the latest building seismic code requirements and accommodate a new larger telescopeand upgraded enclosure. It will be necessary to replace the current dome since a larger slit opening is needed for a larger telescope. MSE will use a thermal management system to remove heat generated by loads from the building, flush excess heat from lower levels, and maintain the observing environment temperature. This paper describes the design approach for redeveloping the CFHT facility for MSE. Once the project is completed the new facility will be almost indistinguishable on the outside from the current CFHT observatory. Past experience and lessons learned from CFHT staff and the astronomical community will be used to create a modern, optimized, and transformative scientific data collecting machine.