Advertisement

Experimental Astronomy

, Volume 37, Issue 2, pp 195–205 | Cite as

Herschel SPIRE FTS telescope model correction

  • Rosalind Hopwood
  • Trevor Fulton
  • Edward T. Polehampton
  • Ivan Valtchanov
  • Dominique Benielli
  • Peter Imhof
  • Tanya Lim
  • Nanyao Lu
  • Nicola Marchili
  • Chris P. Pearson
  • Bruce M. Swinyard
Original Article

Abstract

Emission from the Herschel telescope is the dominant source of radiation for the majority of SPIRE Fourier transform spectrometer (FTS) observations, despite the exceptionally low emissivity of the primary and secondary mirrors. Accurate modelling and removal of the telescope contribution is, therefore, an important and challenging aspect of FTS calibration and data reduction pipeline. A dust-contaminated telescope model with time invariant mirror emissivity was adopted before the Herschel launch. However, measured FTS spectra show a clear evolution of the telescope contribution over the mission and strong need for a correction to the standard telescope model in order to reduce residual background (of up to 7 Jy) in the final data products. Systematic changes in observations of dark sky, taken over the course of the mission, provide a measure of the evolution between observed telescope emission and the telescope model. These dark sky observations have been used to derive a time dependent correction to the telescope emissivity that reduces the systematic error in the continuum of the final FTS spectra to ∼0.35 Jy.

Keywords

SPIRE FTS Calibration Spectroscopy Herschel observatory 

Notes

Acknowledgments

Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. SPIRE has been developed by a consortium of institutes led by Cardiff University (UK) and including Univ. Lethbridge (Canada); NAOC (China); CEA, LAM (France); IFSI, Univ. Padua (Italy); IAC (Spain); Stockholm Observatory (Sweden); Imperial College London, RAL, UCL-MSSL, UKATC, Univ. Sussex (UK); and Caltech, JPL, NHSC, Univ. Colorado (USA). This development has been supported by national funding agencies: CSA (Canada); NAOC (China); CEA, CNES, CNRS (France); ASI (Italy); MCINN (Spain); SNSB (Sweden); STFC (UK); and NASA (USA).

References

  1. 1.
    Fischer, J., Klaassen, T., Hovenier, N.: Cryogenic far infrared laser absorptivity measurements of the herschel space observatory telescope mirror coatings. Appl. Opt. 43, 3765–3771 (2004)ADSCrossRefGoogle Scholar
  2. 2.
    Fulton, T., Hopwood, R., Benielli, D.: Herschel SPIRE FTS pipeline. Astron. Astrophys. (In preparation) (2013)Google Scholar
  3. 3.
    Fulton, T., Hopwood, R., Benielli, D.: Herschel SPIRE FTS relative spectral response calibration. Exp. Astron. (2013) (In this issue)Google Scholar
  4. 4.
    Griffin, M.J., Abergel, A., Abreu, A.: The Herschel SPIRE instrument and its in-flight performance. Astron. Astrophys. 518, L3, 1005.5123 (2010)Google Scholar
  5. 5.
    Pilbratt, G.L., Riedinger, J.R., Passvogel T: Herschel space observatory. An ESA facility for far-infrared and submillimetre astronomy.Astron. Astrophys. 518, L1, 1005.5331 (2010)Google Scholar
  6. 6.
    Swinyard, B.M., Polehampton, E., Hopwood, R.: Calibration of the Herschel SPIRE fourier transform spectrometer. MNRAS. (2013) (Submitted)Google Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • Rosalind Hopwood
    • 1
  • Trevor Fulton
    • 2
    • 3
  • Edward T. Polehampton
    • 3
    • 4
  • Ivan Valtchanov
    • 5
  • Dominique Benielli
    • 6
  • Peter Imhof
    • 2
    • 3
  • Tanya Lim
    • 4
  • Nanyao Lu
    • 7
  • Nicola Marchili
    • 8
  • Chris P. Pearson
    • 4
    • 9
  • Bruce M. Swinyard
    • 4
    • 10
  1. 1.Imperial College London, Blackett LaboratoryLondonUK
  2. 2.Blue Sky SpectroscopyLethbridgeCanada
  3. 3.University of LethbridgeLethbridgeCanada
  4. 4.Rutherford Appleton LaboratoryChiltonUK
  5. 5.ESACMadridSpain
  6. 6.Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille)MarseilleFrance
  7. 7.NHSC/IPACPasadenaUSA
  8. 8.Universitá di PadovaPadovaItaly
  9. 9.The Open UniversityMilton KeynesUK
  10. 10.University College LondonLondonUK

Personalised recommendations