Transforming the Canada France Hawaii Telescope (CFHT) into the Maunakea Spectroscopic Explorer (MSE): A Conceptual Observatory Building and Facilities Design

The Canada France Hawaii TelescopeCorporation (CFHT) plans to repurposeits observatoryon the summit of Maunakea and operate a new wide field spectroscopic survey telescope, the Maunakea Spectroscopic Explorer (MSE). MSE will upgrade the observatorywith a larger 11.25m aperture telescopeand equip it with dedicated instrumentation to capitalize on the site, which has some of the best seeing in the northern hemisphere, and offer its user community the ability to do transformative science. The knowledge and experience of the current CFHT staff will contribute greatly to the engineering of this new facility. MSE will reuse the same building and telescopepier as CFHT. However, it will be necessary to upgrade the support pier to accommodate a bigger telescopeand replace the current dome since a wider slit opening of 12.5 meters in diameter is needed. Once the project is completed the new facility will be almost indistinguishable on the outside from the current CFHT observatory. MSE will build upon CFHT's pioneering work in remote operations, with no staff at the observatoryduring the night, and use modern technologies to reduce daytime maintenance work. This paper describes the design approach for redevelopingthe CFHT facility for MSE including the infrastructure and equipment considerations required to support and facilitate nighttime observations. The building will be designed so existing equipment and infrastructure can be reused wherever possible while meeting new requirement demands. Past experience and lessons learned will be used to create a modern, optimized, and logical layout of the facility. The purpose of this paper is to provide information to readers involved in the MSE project or organizations involved with the redevelopmentof an existing observatoryfacility for a new mission.