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Calibration and performance of the NIKA2 camera at the IRAM 30-m Telescope

2020; EDP Sciences; Volume: 637; Linguagem: Inglês

10.1051/0004-6361/201936220

1432-0746

L. Perotto, N. Ponthieu, J. F. Macías–Pérez, R. Adam, P. A. R. Ade, P. André, A. Andrianasolo, H. Aussel, A. Beelen, A. Benoît, S. Berta, A. Bideaud, O. Bourrion, M. Calvo Gomez, A. Catalano, B. Comis, M. De Petris, F.–X. Désert, S. Doyle, E. F. C. Driessen, P. García, A. Gómez, J. Goupy, D. John, F. Kéruzoré, C. Krämer, B. Ladjelate, G. Lagache, S. Leclercq, J.-F. Lestrade, A. Maury, P. Mauskopf, F. Mayet, A. Monfardini, S. Navarro, J. Peñalver, F. Pierfederici, G. Pisano, V. Revéret, A. Ritacco, C. Romero, H. Roussel, F. Ruppin, K. Schüster, S. Shu, A. Sievers, C. Tucker, R. Zylka,

Calibration and Measurement Techniques

NIKA2 is a dual-band millimetric continuum camera of 2900 Kinetic Inductance Detectors (KID), operating at $150$ and $260\,\rm{GHz}$, installed at the IRAM 30-meter telescope. We present the performance assessment of NIKA2 after one year of observation using a dedicated point-source calibration method, referred to as the \emph{baseline} method. Using a large data set acquired between January 2017 and February 2018 that span the whole range of observing elevations and atmospheric conditions encountered at the IRAM 30-m telescope, we test the stability of the performance parameters. We report an instantaneous field of view (FOV) of 6.5' in diameter, filled with an average fraction of $84\%$ and $90\%$ of valid detectors at $150$ and $260\,\rm{GHz}$, respectively. The beam pattern is characterized by a FWHM of $17.6'' \pm 0.1''$ and $11.1''\pm 0.2''$, and a beam efficiency of $77\% \pm 2\%$ and $55\% \pm 3\%$ at $150$ and $260\,\rm{GHz}$, respectively. The rms calibration uncertainties are about $3\%$ at $150\,\rm{GHz}$ and $6\%$ at $260\,\rm{GHz}$. The absolute calibration uncertainties are of $5\%$ and the systematic calibration uncertainties evaluated at the IRAM 30-m reference Winter observing conditions are below $1\%$ in both channels. The noise equivalent flux density (NEFD) at $150$ and $260\,\rm{GHz}$ are of $9 \pm 1\, \rm{mJy}\cdot s^{1/2}$ and $30 \pm 3\, \rm{mJy}\cdot s^{1/2}$. This state-of-the-art performance confers NIKA2 with mapping speeds of $1388 \pm 174$ and $111 \pm 11 \,\rm{arcmin}^2\cdot \rm{mJy}^{-2}\cdot \rm{h}^{-1}$ at $150$ and $260\,\rm{GHz}$. With these unique capabilities of fast dual-band mapping at high (better that 18'') angular resolution, NIKA2 is providing an unprecedented view of the millimetre Universe.