Construction status of the Daniel K. Inouye solar telescope

The Daniel K. Inouye Solar Telescope (DKIST, renamed in December 2013 from the Advanced Technology Solar Telescope) will be the largest solar facility built when it begins operations in 2019. Designed and developed to meet the needs of critical high resolution and high sensitivity spectral and polarimetric observations of the Sun, the observatory will enable key research for the study of solar magnetism and its influence on the solar wind, flares, coronal mass ejections and solar irradiance variations. The 4-meter class facility will operate over a broad wavelength range (0.38 to 28 microns, initially 0.38 to 5 microns), using a state-of-the-art adaptive optics system to provide diffraction-limited imaging and the ability to resolve features approximately 25 km on the Sun. Five first-light instruments will be available at the start of operations: Visible Broadband Imager (VBI; National Solar Observatory), Visible SpectroPolarimeter (ViSP; NCAR High Altitude Observatory), Visible Tunable Filter (VTF; Kiepenheuer Institut für Sonnenphysik), Diffraction Limited Near InfraRed SpectroPolarimeter (DL-NIRSP; University of Hawai'i, Institute for Astronomy) and the Cryogenic Near InfraRed SpectroPolarimeter (Cryo-NIRSP; University of Hawai'i, Institute for Astronomy). As of mid-2014, the key subsystems have been designed and fabrication is well underway, including the site construction, which began in December 2012. We provide an update on the development of the facilities both on site at the Haleakal Observatories on Maui and the development of components around the world. We present the overall construction and integration schedule leading to the handover to operations in mid 2019. In addition, we outline the evolving challenges being met by the project, spanning the full spectrum of issues covering technical, fiscal, and geographical, that are specific to this project, though with clear counterparts to other large astronomical construction projects.