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Experimental Astronomy

, Volume 37, Issue 2, pp 175–194 | Cite as

SPIRE point source photometry: within the Herschel interactive processing environment (HIPE)

  • Chris PearsonEmail author
  • Tanya Lim
  • Chris North
  • George Bendo
  • Luca Conversi
  • Darren Dowell
  • Matt Griffin
  • Terry Jin
  • Nicolas Laporte
  • Andreas Papageorgiou
  • Bernhard Schulz
  • Dave Shupe
  • Anthony J. Smith
  • Kevin Xu
Original Article

Abstract

The different algorithms appropriate for point source photometry on data from the SPIRE instrument on-board the Herschel Space Observatory, within the Herschel Interactive Processing Environment (HIPE) are compared. Point source photometry of a large ensemble of standard calibration stars and dark sky observations is carried out using the 4 major methods within HIPE: SUSSEXtractor, DAOphot, the SPIRE Timeline Fitter and simple Aperture Photometry. Colour corrections and effective beam areas as a function of the assumed source spectral index are also included to produce a large number of photometric measurements per individual target, in each of the 3 SPIRE bands (250, 350, 500μm), to examine both the accuracy and repeatability of each of the 4 algorithms. It is concluded that for flux densities down to the level of 30mJy that the SPIRE Timeline Fitter is the method of choice. However, at least in the 250 and 350μm bands, all 4 methods provide photometric repeatability better than a few percent down to at approximately 100mJy. The DAOphot method appears in many cases to have a systematic offset of ∼8 % in all SPIRE bands which may be indicative of a sub-optimal aperture correction. In general, aperture photometry is the least reliable method, i.e. largest scatter between observations, especially in the longest wavelength band. At the faintest fluxes, <30mJy, SUSSEXtractor or DAOphot provide a better alternative to the Timeline Fitter.

Keywords

Herschel SPIRE Photometry Calibration 

Notes

Acknowledgments

The authors would like to thank the referee for providing valuable comments that improved the results of this paper. SPIRE has been developed by a consortium of institutes led by Cardiff Univ. (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, UKSA (UK); and NASA (USA). HIPE is a joint development by the Herschel Science Ground Segment Consortium, consisting of ESA, the NASA Herschel Science Center, and the HIFI, PACS and SPIRE consortia.

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Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • Chris Pearson
    • 1
    • 2
    Email author
  • Tanya Lim
    • 1
  • Chris North
    • 3
  • George Bendo
    • 4
  • Luca Conversi
    • 5
  • Darren Dowell
    • 6
  • Matt Griffin
    • 3
  • Terry Jin
    • 7
  • Nicolas Laporte
    • 8
  • Andreas Papageorgiou
    • 3
  • Bernhard Schulz
    • 9
  • Dave Shupe
    • 9
  • Anthony J. Smith
    • 10
    • 11
  • Kevin Xu
    • 9
  1. 1.RAL SpaceSTFC Rutherford Appleton LaboratoryDidcotUK
  2. 2.The Open UniversityMilton KeynesUK
  3. 3.School of Physics and AstronomyCardiff University, The ParadeCardiffUK
  4. 4.UK ALMA Regional Centre Node, Jodrell Bank Centre for AstrophysicsSchool of Physics and Astronomy, University of ManchesterManchesterUK
  5. 5.Herschel Science Centre, ESAC, ESAMadridSpain
  6. 6.NASA Jet Propulsion LaboratoryPasadenaUSA
  7. 7.Department of Physics and AstronomyUniversity College LondonLondonUK
  8. 8.Instituto de Astrofisica de CanariasLa LagunaSpain
  9. 9.NASA Herschel Science Centre, IPACPasadenaUSA
  10. 10.Astronomy CentreUniversity of SussexBrightonUK
  11. 11.Bluesky SpectroscopyLethbridgeCanada

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