S-band Polarization All-Sky Survey (S-PASS): survey description and maps

E. Carretti*, M. Haverkorn, L. Staveley-Smith, G. Bernardi, B. M. Gaensler, M. J. Kesteven, S. Poppi, S. Brown, R. M. Crocker, C. Purcell, D. H. F. M. Schnitzler, X. Sun

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

38 Citations (Scopus)


We present the S-Band Polarization All Sky Survey (S-PASS), a survey of polarized radio emission over the southern sky at Dec. <−1 taken with the Parkes radio telescope at 2.3 GHz. The main aim was to observe at a frequency high enough to avoid strong depolarization at intermediate Galactic latitudes (still present at 1.4 GHz) to study Galactic magnetism, but low enough to retain ample signal-to-noise ratio (S/N) at high latitudes for extragalactic and cosmological science. We developed a new scanning strategy based on long azimuth scans and a corresponding map-making procedure to make recovery of the overall mean signal of Stokes Q and U possible, a long-standing problem with polarization observations. We describe the scanning strategy, map-making procedure and validation tests. The overall mean signal is recovered with a precision better than 0.5 per cent. The maps have a mean sensitivity of 0.81 mK on beam-size scales and show clear polarized signals, typically to within a few degrees of the Galactic plane, with ample S/N everywhere (the typical signal in low-emission regions is 13 mK and 98.6 per cent of pixels have S/N > 3). The largest depolarization areas are in the inner Galaxy, associated with the Sagittarius Arm. We have also computed a rotation measure map combining S-PASS with archival data from the Wilkinson Microwave Anisotropy Probe (WMAP) and Planck experiments. A Stokes I map has been generated, with sensitivity limited to the confusion level of 9 mK.

Original languageEnglish
Pages (from-to)2330-2354
Number of pages25
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Publication statusPublished - 21 Oct 2019


  • magnetic fields
  • polarization
  • radiation mechanisms: non-thermal
  • methods: observational
  • Galaxy: structure
  • diffuse radiation


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