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Monthly Notices of the Royal Astronomical Society 423 (2012) 1293-1299
Intensity and polarization of the atmospheric emission at millimetric wavelengths at Dome Concordia
E.S. Battistelli, G. Amico, A. Baù, L. Bergé1, É. Bréelle2, R. Charlassier2, S. Collin1, A. Cruciani, P. De Bernardis, C. Dufour2, L. Dumoulin1, M. Gervasi, M. Giard3, C. Giordano, Y. Giraud-Héraud2, L. Guglielmi2, J.-C. Hamilton2, J. Landé3, B. Maffei, M. Maiello, S. Marnieros1, S. Masi, A. Passerini, F. Piacentini, M. Piat2, L. Piccirillo, G. Pisano, G. Polenta, C. Rosset2, M. Salatino, A. Schillaci, R. Sordini, S. Spinelli, A. Tartari2, M. Zannoni
BRAIN Collaboration(s)

Atmospheric emission is a dominant source of disturbance in ground-based astronomy at millimetric wavelengths. The Antarctic plateau is recognized as an ideal site for millimetric and submillimetric observations, and the French/Italian base of Dome Concordia (Dome C) is among the best sites on Earth for these observations. In this paper, we present measurements at Dome C of the atmospheric emission in intensity and polarization at a 2-mm wavelength. This is one of the best observational frequencies for cosmic microwave background (CMB) observations when considering cosmic signal intensity, atmospheric transmission, detector sensitivity and foreground removal. Using the B-mode radiation interferometer (BRAIN)-pathfinder experiment, we have performed measurements of the atmospheric emission at 150 GHz. Careful characterization of the airmass synchronous emission has been performed, acquiring more than 380 elevation scans (i.e. 'skydip') during the third BRAIN-pathfinder summer campaign in 2009 December/2010 January. The extremely high transparency of the Antarctic atmosphere over Dome C is proven by the very low measured optical depth, <τI>= 0.050 ± 0.003 ± 0.011, where the first error is statistical and the second is the systematic error. Mid-term stability, over the summer campaign, of the atmosphere emission has also been studied. Adapting the radiative transfer atmosphere emission model am to the particular conditions found at Dome C, we also infer the level of the precipitable water vapor (PWV) content of the atmosphere, which is notoriously the main source of disturbance in millimetric astronomy (? mm). Upper limits on the airmass correlated polarized signal are also placed for the first time. The degree of circular polarization of atmospheric emission is found to be lower than 0.2 per cent [95 per cent confidence level (CL)], while the degree of linear polarization is found to be lower than 0.1 per cent (95 per cent CL). These limits include signal-correlated instrumental spurious polarization.
1 :  CSNSM - Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse
2 :  APC - UMR 7164 - AstroParticule et Cosmologie
3 :  CESR - Centre d'étude spatiale des rayonnements
APC - Cosmologie et Gravitation
Planète et Univers/Astrophysique/Cosmologie et astrophysique extra-galactique

Physique/Astrophysique/Cosmologie et astrophysique extra-galactique
atmospheric effects – instrumentation: polarimeters – site testing – cosmic background radiation
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