Planck pre-launch status: HFI beam expectations from the optical optimisation of the focal plane

¹ The University of Manchester, JBCA, School of Physics and Astronomy, Manchester M13 9PL, UK e-mail: Bruno.maffei@manchester.ac.uk
² Institut d'Astrophysique Spatiale, CNRS & Université Paris 11, Bâtiment 121, 91405 Orsay, France
³ NUI Maynooth, Department of Experimental Physics, Maynooth, Co. Kildare, Ireland
⁴ Cardiff University, School of Physics and Astronomy, The Parade, Cardiff CF24 3AA, UK
⁵ LERMA, CNRS, Observatoire de Paris, 61 Avenue de l'Observatoire, 75014 Paris, France
⁶ Institut d'Astrophysique de Paris, CNRS & Université Paris 6, 98bis Bd Arago, 75014 Paris, France
⁷ Laboratoire de l'Accélérateur Linéaire, CNRS & Université Paris 11, Bâtiment 200, 91898 Orsay, France
⁸ CESR, CNRS-Université, 9 Av. du colonel Roche, BP44346, 31038 Toulouse Cedex 4, France
⁹ Caltech/JPL, Caltech Observational Cosmology, Mail code: 59-33, Pasadena, CA 91125, USA
¹⁰ Princeton University, Dept. of Physics, Princeton, NJ 08544, USA
¹¹ Optical Science Laboratory, Dept. of Physics and Astronomy, UCL, London, WC1E 6BT, UK
¹² School of Physics and Astronomy, North Haugh, St Andrews, Fife KY16 9SS, UK
¹³ Institute of Radiophysics and Electronics, NAS of Ukraine, 12 Proskura St., 61085, Kharkov, Ukraine

Received: 27 July 2009
Accepted: 26 January 2010

Abstract

Planck is a European Space Agency (ESA) satellite, launched in May 2009, which will map the cosmic microwave background anisotropies in intensity and polarisation with unprecedented detail and sensitivity. It will also provide full-sky maps of astrophysical foregrounds. An accurate knowledge of the telescope beam patterns is an essential element for a correct analysis of the acquired astrophysical data. We present a detailed description of the optical design of the High Frequency Instrument (HFI) together with some of the optical performances measured during the calibration campaigns. We report on the evolution of the knowledge of the pre-launch HFI beam patterns when coupled to ideal telescope elements, and on their significance for the HFI data analysis procedure.