Extragalactic number counts at 100 μm, free from cosmic variance

B. Sibthorpe*, R. J. Ivison, R. J. Massey, I. G. Roseboom, P. P. van der Werf, B. C. Matthews, J. S. Greaves

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


We use data from the Disc Emission via a Bias-free Reconnaissance in the Infrared/ Submillimetre (DEBRIS) survey, taken at 100 μm with the Photoconductor Array Camera and Spectrometer instrument on board the Herschel Space Observatory, to make a cosmic variance independent measurement of the extragalactic number counts. These data consist of 323 small-area mapping observations performed uniformly across the sky, and thus represent a sparse sampling of the astronomical sky with an effective coverage of ~2.5 deg2. We find our cosmic variance independent analysis to be consistent with previous count measurements made using relatively small area surveys. Furthermore, we find no statistically significant cosmic variance on any scale within the errors of our data. Finally, we interpret these results to estimate the probability of galaxy source confusion in the study of debris discs.

Original languageEnglish
JournalMonthly Notices of the Royal Astronomical Society: Letters
Issue number1
Publication statusPublished - 24 Oct 2012


  • Cosmologyc
  • Galaxies
  • Miscellaneous - large-scale structure of Universe - infrared


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