S-band Polarization All-Sky Survey (S-PASS): survey description and maps
Date Issued
2019
Author(s)
•
Haverkorn, M.
•
Staveley-Smith, L.
•
•
Gaensler, B. M.
•
Kesteven, M. J.
•
•
Brown, S.
•
Crocker, R. M.
•
Purcell, C.
•
Schnitzeler, D. H. F. M.
•
Sun, X.
Abstract
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.
Volume
489
Issue
2
Start page
2330
Issn Identifier
0035-8711
Ads BibCode
2019MNRAS.489.2330C
Rights
open.access
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