Characterization of the in-flight properties of the Planck telescope

J. A. Tauber, P. H. Nielsen, A. Martin-Polegre, B. Crill, F. Cuttaia, K. Ganga, J. Gudmundsson, W. Jones, C. Lawrence, P. Meinhold, H. U. Nørgaard-Nielsen, C. A. Oxborrow, B. Partridge, G. Roudier, M. Sandri, D. Scott, L. Terenzi, F. Villa, J. P. Bernard, C. BuriganaE. Franceschi, H. Kurki-Suonio, N. Mandolesi, J. L. Puget, L. Toffolatti

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Abstract

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

Keywords

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

Cite this

Tauber, J. A., Nielsen, P. H., Martin-Polegre, A., Crill, B., Cuttaia, F., Ganga, K., ... Toffolatti, L. (2019). Characterization of the in-flight properties of the Planck telescope. Astronomy and Astrophysics, 622, [A55]. https://doi.org/10.1051/0004-6361/201833150
Tauber, J. A. ; Nielsen, P. H. ; Martin-Polegre, A. ; Crill, B. ; Cuttaia, F. ; Ganga, K. ; Gudmundsson, J. ; Jones, W. ; Lawrence, C. ; Meinhold, P. ; Nørgaard-Nielsen, H. U. ; Oxborrow, C. A. ; Partridge, B. ; Roudier, G. ; Sandri, M. ; Scott, D. ; Terenzi, L. ; Villa, F. ; Bernard, J. P. ; Burigana, C. ; Franceschi, E. ; Kurki-Suonio, H. ; Mandolesi, N. ; Puget, J. L. ; Toffolatti, L. / Characterization of the in-flight properties of the Planck telescope. In: Astronomy and Astrophysics. 2019 ; Vol. 622.
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abstract = "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.",
keywords = "Telescopes, Methods: data analysis, Space vehicles: instruments",
author = "Tauber, {J. A.} and Nielsen, {P. H.} and A. Martin-Polegre and B. Crill and F. Cuttaia and K. Ganga and J. Gudmundsson and W. Jones and C. Lawrence and P. Meinhold and N{\o}rgaard-Nielsen, {H. U.} and Oxborrow, {C. A.} and B. Partridge and G. Roudier and M. Sandri and D. Scott and L. Terenzi and F. Villa and Bernard, {J. P.} and C. Burigana and E. Franceschi and H. Kurki-Suonio and N. Mandolesi and Puget, {J. L.} and L. Toffolatti",
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Tauber, JA, Nielsen, PH, Martin-Polegre, A, Crill, B, Cuttaia, F, Ganga, K, Gudmundsson, J, Jones, W, Lawrence, C, Meinhold, P, Nørgaard-Nielsen, HU, Oxborrow, CA, Partridge, B, Roudier, G, Sandri, M, Scott, D, Terenzi, L, Villa, F, Bernard, JP, Burigana, C, Franceschi, E, Kurki-Suonio, H, Mandolesi, N, Puget, JL & Toffolatti, L 2019, 'Characterization of the in-flight properties of the Planck telescope', Astronomy and Astrophysics, vol. 622, A55. https://doi.org/10.1051/0004-6361/201833150

Characterization of the in-flight properties of the Planck telescope. / Tauber, J. A.; Nielsen, P. H.; Martin-Polegre, A.; Crill, B.; Cuttaia, F.; Ganga, K.; Gudmundsson, J.; Jones, W.; Lawrence, C.; Meinhold, P.; Nørgaard-Nielsen, H. U.; Oxborrow, C. A.; Partridge, B.; Roudier, G.; Sandri, M.; Scott, D.; Terenzi, L.; Villa, F.; Bernard, J. P.; Burigana, C.; Franceschi, E.; Kurki-Suonio, H.; Mandolesi, N.; Puget, J. L.; Toffolatti, L.

In: Astronomy and Astrophysics, Vol. 622, A55, 2019.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Characterization of the in-flight properties of the Planck telescope

AU - Tauber, J. A.

AU - Nielsen, P. H.

AU - Martin-Polegre, A.

AU - Crill, B.

AU - Cuttaia, F.

AU - Ganga, K.

AU - Gudmundsson, J.

AU - Jones, W.

AU - Lawrence, C.

AU - Meinhold, P.

AU - Nørgaard-Nielsen, H. U.

AU - Oxborrow, C. A.

AU - Partridge, B.

AU - Roudier, G.

AU - Sandri, M.

AU - Scott, D.

AU - Terenzi, L.

AU - Villa, F.

AU - Bernard, J. P.

AU - Burigana, C.

AU - Franceschi, E.

AU - Kurki-Suonio, H.

AU - Mandolesi, N.

AU - Puget, J. L.

AU - Toffolatti, L.

PY - 2019

Y1 - 2019

N2 - 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.

AB - 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.

KW - Telescopes

KW - Methods: data analysis

KW - Space vehicles: instruments

U2 - 10.1051/0004-6361/201833150

DO - 10.1051/0004-6361/201833150

M3 - Journal article

VL - 622

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

SN - 0004-6361

M1 - A55

ER -

Tauber JA, Nielsen PH, Martin-Polegre A, Crill B, Cuttaia F, Ganga K et al. Characterization of the in-flight properties of the Planck telescope. Astronomy and Astrophysics. 2019;622. A55. https://doi.org/10.1051/0004-6361/201833150