Development status of the mid-infrared two-field camera and spectrograph MIMIZUKU for the TAO 6.5-m Telescope

MIMIZUKU is the first-generation mid-infrared instrument for the university of Tokyo Atacama Observatory (TAO) 6.5-m telescope. MIMIZUKU provides imaging and spectroscopic monitoring capabilities in a wide wavelength range from 2 to 38 μm, including unique bands like 2.7-μm and 30-μm band. Recently, we decided to add spectroscopic functions, KL-band mode (λ= 2.1-4.0 μm; R =λ/Δλ ~ 210) and 2.7-μm band mode ( λ= 2.4-2.95 μm; R ~ 620), and continuous spectroscopic coverage from 2.1 to 26 μm is realized by this update. Their optical designing is completed, and fabrications of optical elements are ongoing. As recent progress, we also report the completion of the cryogenic system and optics. The cryogenic system has been updated by changing materials and structures of thermal links, and the temperatures of the optical bench and detector mounting stages finally achieved required temperatures. Their stability against instrument attitude is also confirmed through an inclination test. As for the optics, its gold-plated mirrors have been recovered from galvanic corrosion by refabrication and reconstruction. Enough image quality and stability are confirmed by room-temperature tests. MIMIZUKU is intended to be completed in this autumn, and commissioning at the Subaru telescope and scientific operations on the TAO telescope are planned in 2017 and around 2019, respectively. In this paper, these development activities and future prospects of MIMIZUKU are reported.