CONCERTO at APEX: Installation and Technical Commissioning

We describe the deployment and first tests on sky of CONCERTO, a large field-of-view (18.6 arc-min) spectral-imaging instrument. The instrument operates in the range 130–310 GHz from the APEX 12-metres telescope located at 5100 m a.s.l. on the Chajnantor plateau. Spectra with R= ν / Δ ν ≤ 300 are obtained using a fast (2.5 Hz mechanical frequency) Fourier Transform Spectrometer (FTS), coupled to a continuous dilution cryostat with a base temperature of 60 mK. Two 2152-pixels arrays of Lumped Element Kinetic Inductance Detectors (LEKID) are installed in the cryostat that also contains the cold optics and the front-end electronics. CONCERTO, installed in April 2021, generates more than 20k spectra per second during observations. We describe the final development phases, the installation and the first results obtained on sky.