Context . CarbON CII line in post-rEionisation and ReionisaTiOn epoch (CONCERTO) instrument is a low-resolution mapping spectrometer based on lumped element kinetic inductance detector (LEKIDs) technology, operating at 130-310 GHz. It was installed on the 12-metre APEX telescope in Chile in April 2021 and was in operation until May 2023. CONCERTO’s main goals were the observation of [CII]-emission line fluctuations at high redshift and of the Sunyaev–Zel’dovich (SZ) signal from galaxy clusters. Aims . We present the data processing algorithms and the performance of CONCERTO in continuum by analysing the data from the commissioning and scientific observations. Methods . We developed a standard data processing pipeline to proceed from the raw data to continuum maps. Using a large dataset of calibrators (Uranus, Mars, and quasars) acquired in 2021 and 2022 at the APEX telescope across a wide range of atmospheric conditions, we measured the CONCERTO continuum performance and tested its stability against observing conditions. Further, using observations on the COSMOS field and observations targeting a distant sub-millimetre galaxy in the UDS field, we assessed the robustness of the CONCERTO performance on faint sources and compared our measurements with expectations. Results . The beam pattern is characterised by an effective full width at half maximum (FWHM) of 31.9 ± 0.6″ and 34.4 ± 1.0″ for high-frequency (HF) and low-frequency (LF) bands, respectively. The main beam is slightly elongated with a mean eccentricity of 0.46. Two error beams of ~65″ and ~130″ are characterised, allowing us to estimate a main beam efficiency of ~0.52. The field of view is accurately reconstructed and presents coherent distortions between the HF and LF arrays. LEKID parameters were robustly determined for 80% of the read tones. Cross-talks between LEKIDs are the first cause of flagging, followed by an excess of eccentricity for ~10% of the LEKIDs, all located in a given region of the field of view. Of the 44 scans of Uranus selected for the absolute photometric calibration, 72.5% and 78.2% of the LEKIDs were selected as valid detectors with a probability >70%. By comparing the Uranus measurements with a model, we obtain calibration factors of 19.5±0.6 Hz Jy −1 and 25.6±0.9 Hz Jy −1 for HF and LF, respectively. The point-source continuum measurement uncertainties are 3.0% and 3.4% for the HF and LF bands, ignoring the uncertainty in the model (which is <2%). This demonstrates the accuracy of the methods we deployed to process the data. Finally, the RMS of CONCERTO maps is verified to evolve as proportional to the inverse square root of the integration time. The measured noise-equivalent flux densities (NEFDs) for HF and LF are 115±2 mJy beam −1 s 1/2 and 95±1 mJy beam −1 s 1/2 , respectively, obtained using CONCERTO data on the COSMOS field for a mean precipitable water vapour (pwv) and elevation of 0.81 mm and 55.7 deg. Conclusions . CONCERTO has unique capabilities in fast dual-band spectral mapping at ~30 arcsec resolution and with a ~18.5 arcmin instantaneous field of view. CONCERTO’s performance in continuum is perfectly in line with expectations.

CONCERTO (CarbON CII line in post-rEionisation and ReionisaTiOn) is a large field-of-view (FoV) spectro-imager that has been installed on the Cassegrain Cabin of Atacama Pathfinder EXperiment (APEX) telescope in April 2021. CONCERTO hosts 2 focal planes and a total number of 4000 Kinetic Inductance Detectors (KID), with an instantaneous FoV of 18.6 arcminutes in the range of 130-310 GHz. The spectral resolution can be easily tuned down to 1 GHz depending on the scientific target. The scientific program of CONCERTO has many objectives, with two main programs focused on mapping the fluctuations of the [CII] line intensity in the reionisation and postreionisation epoch (4.5<z<8.5), and on studying galaxy clusters via the thermal and kinetic Sunyaev-Zel’dovich (SZ) effect. CONCERTO will also measure the dust and molecular gas contents of local and intermediate-redshift galaxies, it will study the Galactic star-forming clouds and finally it will observe the CO intensity fluctuations arising from 0.3<z<2 galaxies. The design of the instrument, installation at APEX and current status of the commissioning phase and science verification will be presented. Also we describe the deployment and first on-sky tests performed between April and June 2021.

We describe the deployment and first tests on Sky of CONCERTO, a large field-of-view (18.6arc-min) spectral-imaging instrument. The instrument operates in the range 130-310GHz from the APEX 12-meters telescope located at 5100m a.s.l. on the Chajnantor plateau. Spectra with R=1-300 are obtained using a fast (2.5Hz mechanical frequency) Fourier Transform Spectrometer (FTS), coupled to a continuous dilution cryostat with a base temperature of 60mK. 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.

Context.Characterising the large-scale structure in the Universe from present times to the high redshift epoch of reionisation is essential to constraining the cosmology, the history of star formation, and reionisation, to measuring the gas content of the Universe, and to obtaining a better understanding of the physical processes that drive galaxy formation and evolution. Using the integrated emission from unresolved galaxies or gas clouds, line intensity mapping (LIM) provides a new observational window to measure the larger properties of structures. This very promising technique motivates the community to plan for LIM experiments.Aims.We describe the development of a large field-of-view instrument, named CONCERTO (for CarbON CII line in post-rEionisation and ReionisaTiOn epoch), operating in the range 130–310 GHz from the APEX 12-m telescope (5100 m above sea level). CONCERTO is a low-resolution spectrometer based on the lumped element kinetic inductance detectors (LEKID) technology. Spectra are obtained using a fast Fourier transform spectrometer (FTS), coupled to a dilution cryostat with a base temperature of 0.1 K. Two two kilo-pixel arrays of LEKID are mounted inside the cryostat that also contains the cold optics and the front-end electronics.Methods.We present, in detail, the technological choices leading to the instrumental concept, together with the design and fabrication of the instrument and preliminary laboratory tests on the detectors. We also give our best estimates for CONCERTO sensitivity and give predictions for two of the main scientific goals of CONCERTO, that is, a [CII]-intensity mapping survey and observations of galaxy clusters.Results.We provide a detailed description of the instrument design. Based on realistic comparisons with existing instruments developed by our group (NIKA, NIKA2, and KISS), and on the laboratory characterisation of our detectors, we provide an estimate for CONCERTO sensitivity on the sky. Finally, we describe, in detail, two of the main scientific goals offered by CONCERTO at APEX.

The New IRAM KID Arrays 2 (NIKA2) consortium has just finished installing and commissioning a millimetre camera on the IRAM 30 m telescope. It is a dual-band camera operating with three frequency multiplexed kilo-pixels arrays of Lumped Element Kinetic Inductance Detectors (LEKID) cooled at 150 mK, designed to observe the intensity and polarisation of the sky at 260 and 150 GHz (1.15 and 2 mm). NIKA2 is today an IRAM resident instrument for millimetre astronomy, such as Intra Cluster Medium from intermediate to distant clusters and so for the follow-up of Planck satellite detected clusters, high redshift sources and quasars, early stages of star formation and nearby galaxies emission. We present an overview of the instrument performance as it has been evaluated at the end of the commissioning phase.

New IRAM KID array 2 (NIKA2) is a camera dedicated to millimeter-wave astronomy based upon kilopixel arrays of kinetic inductance detectors [1] (KID). The pathfinder instrument, NIKA [2], has already shown state-of-the-art detector performance. NIKA2 builds upon this experience but goes one step further, increasing the total pixel count by a factor \(\sim \)10 while maintaining the same per pixel performance. For the next decade, this camera will be the resident photometric instrument of the Institut de Radio Astronomie Millimetrique (IRAM) 30 m telescopes in Sierra Nevada (Spain). In this paper, we give an overview of the main components of NIKA2 and describe the achieved detector performance. The camera has been permanently installed at the IRAM 30 m telescope in October 2015. It will be made accessible to the scientific community at the end of 2016, after a 1-year commissioning period. When this happens, NIKA2 will become a fundamental tool for astronomers worldwide.