Characterization of the in-flight properties of the Planck telescope

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

doi:10.1051/0004-6361/201833150

Characterization of the in-flight properties of the Planck telescope

J. A. Tauber
, P. H. Nielsen
, A. Martín-Polegre
, B. Crill
, F. Cuttaia
, K. Ganga
, J. Gudmundsson
, W. Jones
, C. Lawrence
, P. Meinhold
, H. U. Norgaard-Nielsen
, C. A. Oxborrow
, B. Partridge
, G. Roudier
, M. Sandri
, D. Scott
, L. Terenzi
, F. Villa
, J. P. Bernard
, C. Burigana

E. Franceschi, H. Kurki-Suonio, N. Mandolesi, J. L. Puget, L. Toffolatti

Faculty of Physical Sciences

University of Iceland

Research output: Contribution to journal › Article › peer-review

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 1° 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 language	English
Article number	A55
Journal	Astronomy and Astrophysics
Volume	622
DOIs	https://doi.org/10.1051/0004-6361/201833150
Publication status	Published - 1 Feb 2019

Bibliographical note

Funding Information: 1 Planck (http://www.esa.int/Planck) is a project of the European Space Agency (ESA), with instruments provided by two scientific Consortia funded by ESA member states and led by Principal Investigators from France and Italy, telescope reflectors provided through a collaboration between ESA and a scientific consortium led and funded by Denmark, and additional contributions from NASA (USA). Funding Information: Acknowledgements. This paper has been reviewed internally by the Planck Collaboration. A description of the Planck Collaboration and a list of its members, indicating which technical or scientific activities they have been involved in, can be found at http://www.cosmos.esa.int/web/planck/ planck-collaboration. The Planck Collaboration acknowledges the support of: ESA; CNES and CNRS/INSU-IN2P3-INP (France); ASI, CNR, and INAF (Italy); NASA and DoE (USA); STFC and UKSA (UK); CSIC, MICINN, and JA (Spain); Tekes, AoF, and CSC (Finland); DLR and MPG (Germany); CSA (Canada); DTU Space (Denmark); SER/SSO (Switzerland); RCN (Norway); SFI (Ireland); FCT/MCTES (Portugal); and DEISA (EU). The GRASP-based modelling work described here was carried out largely by Per Nielsen of TICRA, and benefitted from TICRA’s long-standing, dedicated, and very productive involvement in the Planck mission covering, among others the specification, prediction, and characterization of the optical system of Planck. Publisher Copyright: © ESO 2019.

Other keywords

data analysis
instruments
methods
space vehicles
telescopes

Access to Document

10.1051/0004-6361/201833150

Cite this

Tauber, J. A., Nielsen, P. H., Martín-Polegre, A., Crill, B., Cuttaia, F., Ganga, K., Gudmundsson, J., Jones, W., Lawrence, C., Meinhold, P., Norgaard-Nielsen, H. U., Oxborrow, C. A., Partridge, B., Roudier, G., Sandri, M., Scott, D., Terenzi, L., Villa, F., Bernard, J. P., ... Toffolatti, L. (2019). Characterization of the in-flight properties of the Planck telescope. Astronomy and Astrophysics, 622, Article A55. https://doi.org/10.1051/0004-6361/201833150

@article{b4479a2bf59f42a1b12bd89cecd7a2fa,

title = "Characterization of the in-flight properties of the Planck telescope",

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 1° 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 = "data analysis, instruments, methods, space vehicles, telescopes",

author = "Tauber, \{J. A.\} and Nielsen, \{P. H.\} and A. Mart{\'i}n-Polegre and B. Crill and F. Cuttaia and K. Ganga and J. Gudmundsson and W. Jones and C. Lawrence and P. Meinhold and Norgaard-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",

note = "Funding Information: 1 Planck (http://www.esa.int/Planck) is a project of the European Space Agency (ESA), with instruments provided by two scientific Consortia funded by ESA member states and led by Principal Investigators from France and Italy, telescope reflectors provided through a collaboration between ESA and a scientific consortium led and funded by Denmark, and additional contributions from NASA (USA). Funding Information: Acknowledgements. This paper has been reviewed internally by the Planck Collaboration. A description of the Planck Collaboration and a list of its members, indicating which technical or scientific activities they have been involved in, can be found at http://www.cosmos.esa.int/web/planck/ planck-collaboration. The Planck Collaboration acknowledges the support of: ESA; CNES and CNRS/INSU-IN2P3-INP (France); ASI, CNR, and INAF (Italy); NASA and DoE (USA); STFC and UKSA (UK); CSIC, MICINN, and JA (Spain); Tekes, AoF, and CSC (Finland); DLR and MPG (Germany); CSA (Canada); DTU Space (Denmark); SER/SSO (Switzerland); RCN (Norway); SFI (Ireland); FCT/MCTES (Portugal); and DEISA (EU). The GRASP-based modelling work described here was carried out largely by Per Nielsen of TICRA, and benefitted from TICRA{\textquoteright}s long-standing, dedicated, and very productive involvement in the Planck mission covering, among others the specification, prediction, and characterization of the optical system of Planck. Publisher Copyright: {\textcopyright} ESO 2019.",

year = "2019",

month = feb,

day = "1",

doi = "10.1051/0004-6361/201833150",

language = "English",

volume = "622",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

}

Tauber, JA, Nielsen, PH, Martín-Polegre, A, Crill, B, Cuttaia, F, Ganga, K, Gudmundsson, J, Jones, W, Lawrence, C, Meinhold, P, Norgaard-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

TY - JOUR

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

AU - Tauber, J. A.

AU - Nielsen, P. H.

AU - Martín-Polegre, A.

AU - Crill, B.

AU - Cuttaia, F.

AU - Ganga, K.

AU - Gudmundsson, J.

AU - Jones, W.

AU - Lawrence, C.

AU - Meinhold, P.

AU - Norgaard-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.

N1 - Funding Information: 1 Planck (http://www.esa.int/Planck) is a project of the European Space Agency (ESA), with instruments provided by two scientific Consortia funded by ESA member states and led by Principal Investigators from France and Italy, telescope reflectors provided through a collaboration between ESA and a scientific consortium led and funded by Denmark, and additional contributions from NASA (USA). Funding Information: Acknowledgements. This paper has been reviewed internally by the Planck Collaboration. A description of the Planck Collaboration and a list of its members, indicating which technical or scientific activities they have been involved in, can be found at http://www.cosmos.esa.int/web/planck/ planck-collaboration. The Planck Collaboration acknowledges the support of: ESA; CNES and CNRS/INSU-IN2P3-INP (France); ASI, CNR, and INAF (Italy); NASA and DoE (USA); STFC and UKSA (UK); CSIC, MICINN, and JA (Spain); Tekes, AoF, and CSC (Finland); DLR and MPG (Germany); CSA (Canada); DTU Space (Denmark); SER/SSO (Switzerland); RCN (Norway); SFI (Ireland); FCT/MCTES (Portugal); and DEISA (EU). The GRASP-based modelling work described here was carried out largely by Per Nielsen of TICRA, and benefitted from TICRA’s long-standing, dedicated, and very productive involvement in the Planck mission covering, among others the specification, prediction, and characterization of the optical system of Planck. Publisher Copyright: © ESO 2019.

PY - 2019/2/1

Y1 - 2019/2/1

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 1° 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 1° 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 - data analysis

KW - instruments

KW - methods

KW - space vehicles

KW - telescopes

UR - https://www.scopus.com/pages/publications/85060986639

U2 - 10.1051/0004-6361/201833150

DO - 10.1051/0004-6361/201833150

M3 - Article

SN - 0004-6361

VL - 622

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - A55

ER -

Characterization of the in-flight properties of the Planck telescope

Abstract

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