Planck 2013 results: IX. HFI spectral response

Research output: Contribution to journalArticle


  • P. A. R. Ade
  • N. Aghanim
  • C. Armitage-Caplan
  • M. Arnaud
  • M. Ashdown
  • F. Atrio-Barandela
  • J. Aumont
  • C. Baccigalupi
  • A. J. Banday
  • R. B. Barreiro
  • E. Battaner
  • K. Benabed
  • A. Benoit
  • A. Benoit-Levy
  • J. -P. Bernard
  • M. Bersanelli
  • P. Bielewicz
  • J. Bobin
  • J. J. Bock
  • J. R. Bond
  • J. Borrill
  • F. R. Bouchet
  • F. Boulanger
  • M. Bridges
  • M. Bucher
  • C. Burigana
  • J. -F. Cardoso
  • A. Catalano
  • A. Challinor
  • A. Chamballu
  • R. -R. Chary
  • X. Chen
  • H. C. Chiang
  • L. -Y Chiang
  • P. R. Christensen
  • S. Church
  • D. L. Clements
  • S. Colombi
  • L. P. L. Colombo
  • C. Combet
  • B. Comis
  • F. Couchot
  • A. Coulais
  • B. P. Crill
  • A. Curto
  • F. Cuttaia
  • L. Danese
  • R. D. Davies
  • P. de Bernardis
  • A. de Rosa
  • Planck Collaboration

Research units

  • University of Salamanca
  • University of Granada
  • Univ Grenoble 1, Centre National de la Recherche Scientifique (CNRS), Joseph Fourier University, Inst Neel
  • University of California at Berkeley
  • Telecom Paris Tech
  • Acad Sinica, Academia Sinica - Taiwan, Inst Astron & Astrophys
  • Cardiff University
  • Univ Paris 11, Centre National de la Recherche Scientifique (CNRS), University of Paris Sud - Paris XI, CNRS, Inst Astrophys Spatiale, UMR 8617)
  • CEA Saclay, CEA, Centre National de la Recherche Scientifique (CNRS), PRES University Sorbonne Paris Cite, University of Paris Diderot - Paris VII, Univ Paris Diderot, CNRS, CEA DSM,IRFU,Serv Astrophys,Lab AIM
  • University of Cambridge
  • International School for Advanced Studies
  • Univ Paris 06, Pierre & Marie Curie University - Paris 6, UMR7095
  • Univ Cantabria, Consejo Superior de Investigaciones Cientificas (CSIC), Universidad de Cantabria, CSIC, Inst Fis Cantabria
  • CERN, European Organization for Nuclear Research (CERN), PH TH, Div Theory
  • INAF IASF Milano, Istituto Nazionale Astrofisica - Italy
  • California Institute of Technology
  • University of Toronto
  • Univ Paris Diderot, CEA, PRES University Sorbonne Paris Cite, University of Paris Diderot - Paris VII, PSL Research University Paris, Observatoire de Paris, Centre National de la Recherche Scientifique (CNRS), Observ Paris, Sorbonne Paris Cite, CNRS IN2P3,CEA lrfu,APC
  • IASF Bologna, Istituto Nazionale Astrofisica - Italy, INAF
  • Univ Grenoble 1, Centre National de la Recherche Scientifique (CNRS), Institut National Polytechnique de Grenoble, Joseph Fourier University, National Institute of Nuclear & Particle Physics (IN2P3), Lab Phys Subatom & Cosmol, CNRS, Inst Natl Polytech Grenoble,IN2P3
  • Princeton University
  • Niels Bohr Inst, Niels Bohr Institute, University of Copenhagen
  • Stanford University
  • Imperial College London
  • Univ Paris 11, Centre National de la Recherche Scientifique (CNRS), National Institute of Nuclear & Particle Physics (IN2P3), University of Paris Sud - Paris XI, CNRS, IN2P3, LAL
  • Observ Paris, Centre National de la Recherche Scientifique (CNRS)
  • Univ Manchester, Jodrell Bank Centre for Astrophysics, University of Manchester, Sch Phys & Astron, Jodrell Bank Ctr Astrophys
  • Sapienza University Rome


The Planck High Frequency Instrument (HFI) spectral response was determined through a series of ground based tests conducted with the HFI focal plane in a cryogenic environment prior to launch. The main goal of the spectral transmission tests was to measure the relative spectral response (including the level of out-of-band signal rejection) of all HFI detectors to a known source of electromagnetic radiation individually. This was determined by measuring the interferometric output of a continuously scanned Fourier transform spectrometer with all HFI detectors. As there is no on-board spectrometer within HFI, the ground-based spectral response experiments provide the definitive data set for the relative spectral calibration of the HFI. Knowledge of the relative variations in the spectral response between HFI detectors allows for a more thorough analysis of the HFI data. The spectral response of the HFI is used in Planck data analysis and component separation, this includes extraction of CO emission observed within Planck bands, dust emission, Sunyaev-Zeldovich sources, and intensity to polarization leakage. The HFI spectral response data have also been used to provide unit conversion and colour correction analysis tools.

While previous papers describe the pre-flight experiments conducted on the Planck HFI, this paper focusses on the analysis of the pre-flight spectral response measurements and the derivation of data products, e.g. band-average spectra, unit conversion coefficients, and colour correction coefficients, all with related uncertainties. Verifications of the HFI spectral response data are provided through comparisons with photometric HFI flight data. This validation includes use of HFI zodiacal emission observations to demonstrate out-of-band spectral signal rejection better than 10(8). The accuracy of the HFI relative spectral response data is verified through comparison with complementary flight-data based unit conversion coefficients and colour correction coefficients. These coefficients include those based upon HFI observations of CO, dust, and Sunyaev-Zeldovich emission. General agreement is observed between the ground-based spectral characterization of HFI and corresponding in-flight observations, within the quoted uncertainty of each; explanations are provided for any discrepancies.


Original languageEnglish
Article numberA9
Number of pages27
JournalAstronomy and Astrophysics
Publication statusPublished - Nov 2014
MoE publication typeA1 Journal article-refereed

    Research areas

  • instrumentation: detectors, instrumentation: photometers, space vehicles: instruments, cosmology: observations, cosmic background radiation, HIGH-FREQUENCY INSTRUMENT, COBE FIRAS INSTRUMENT, MOLECULAR CLOUDS, MICROWAVE, SPECTROSCOPY, CALIBRATION

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