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Description
We present a Stokes I, Q and U survey at 189MHz with the Murchison Widefield Array 32 element prototype covering 2400deg^2^. The survey has a 15.6' angular resolution and achieves a noise level of 15mJy/beam. We demonstrate a novel interferometric data analysis that involves calibration of drift scan data, integration through the co-addition of warped snapshot images, and deconvolution of the point-spread function through forward modeling. We present a point source catalog down to a flux limit of 4Jy. We detect polarization from only one of the sources, PMN J0351-2744, at a level of 1.8%+/-0.4%, whereas the remaining sources have a polarization fraction below 2%. Compared to a reported average value of 7% at 1.4GHz, the polarization fraction of compact sources significantly decreases at low frequencies. We find a wealth of diffuse polarized emission across a large area of the survey with a maximum peak of ~13K, primarily with positive rotation measure values smaller than +10rad/m2. The small values observed indicate that the emission is likely to have a local origin (closer than a few hundred parsecs). There is a large sky area at {alpha}>=2^h^30^m^ where the diffuse polarized emission rms is fainter than 1K. Within this area of low Galactic polarization we characterize the foreground properties in a cold sky patch at ({alpha},{delta})=(4^h^,-27.6{deg}) in terms of three-dimensional power spectra.
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