Characterization of the in-flight properties of the Planck telescope

Research output: Contribution to journalJournal article – Annual report year: 2019Researchpeer-review

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  • Author: Tauber, J. A.

    ESTEC, Netherlands

  • Author: Nielsen, P. H.

    TICRA, Denmark

  • Author: Martín-Polegre, A.

    ESTEC, Netherlands

  • Author: Crill, B.

    California Institute of Technology, United States

  • Author: Cuttaia, F.

    National Institute for Astrophysics, Italy

  • Author: Ganga, K.

    University Paris Diderot - Paris 7, France

  • Author: Gudmundsson, J.

    Princeton University, United States

  • Author: Jones, W.

    Princeton University, United States

  • Author: Lawrence, C. R.

    California Institute of Technology, United States

  • Author: Meinhold, P. R.

    University of California at Santa Barbara, United States

  • Author: Nørgaard-Nielsen, H. U.

    Astrophysics and Atmospheric Physics, National Space Institute, Technical University of Denmark, Elektrovej, 2800, Kgs. Lyngby, Denmark

  • Author: Oxborrow, C. A.

    Astrophysics and Atmospheric Physics, National Space Institute, Technical University of Denmark, Elektrovej, 2800, Kgs. Lyngby, Denmark

  • Author: Partridge, B.

    Haverford College, United States

  • Author: Roudier, G.

    University Paris Diderot - Paris 7, France

  • Author: Sandri, M.

    National Institute for Astrophysics, Italy

  • Author: Scott, D.

    University of British Columbia, Canada

  • Author: Terenzi, L.

    National Institute for Astrophysics, Italy

  • Author: Villa, F

    National Institute for Astrophysics, Italy

  • Author: Bernard, J. -P.

    Centre National de la Recherche Scientifique, France

  • Author: Burigana, C.

    Università degli studi di Ferrara, Italy

  • Author: Franceschi, E.

    National Institute for Astrophysics, Italy

  • Author: Kurki-Suonio, H.

    University of Helsinki, Finland

  • Author: Mandolesi, N.

    Università degli studi di Ferrara, Italy

  • Author: Puget, J. -L.

    Universite Paris-Saclay, France

  • Author: Toffolatti, L.

    University of Oviedo, Spain

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The European Space Agency's Planck satellite was launched on 14 May 2009, and surveyed the sky stably and continuously between August 2009 and October 2013. The scientific analysis of the Planck data requires understanding the optical response of its detectors, which originates partly from a physical model of the optical system. In this paper, we use in-flight measurements of planets within similar to 1 degrees of boresight to estimate the geometrical properties of the telescope and focal plane. First, we use observed grating lobes to measure the amplitude of mechanical dimpling of the reflectors, which is caused by the hexagonal honeycomb structure of the carbon fibre reflectors. We find that the dimpling amplitude on the two reflectors is larger than expected from the ground, by 20% on the secondary and at least a factor of 2 on the primary. Second, we use the main beam shapes of 26 detectors to investigate the alignment of the various elements of the optical system, as well as the large-scale deformations of the reflectors. We develop a metric to guide an iterative fitting scheme, and are able to determine a new geometric model that fits the in-flight measurements better than the pre-flight prediction according to this metric. The new alignment model is within the mechanical tolerances expected from the ground, with some specific but minor exceptions. We find that the reflectors contain large-scale sinusoidal deformations most probably related to the mechanical supports. In spite of the better overall fit, the new model still does not fit the beam measurements at a level compatible with the needs of cosmological analysis. Nonetheless, future analysis of the Planck data would benefit from taking into account some of the features of the new model. The analysis described here exemplifies some of the limitations of in-flight retrieval of the geometry of an optical system similar to that of Planck, and provides useful information for similar efforts in future experiments.
Original languageEnglish
Article numberA55
JournalAstronomy and Astrophysics
Volume622
Number of pages21
ISSN0004-6361
DOIs
Publication statusPublished - 2019
CitationsWeb of Science® Times Cited: No match on DOI

    Research areas

  • Telescopes, Methods: data analysis, Space vehicles: instruments

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