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T.L. Landecker, B. Uyan{i}ker, R. Kothes (National Research Council Canada, Dominion Radio Astrophysical Observatory)
The Canadian Galactic Plane Survey (CGPS) is creating images of total intensity and polarized emission at 1420 MHz with arcminute angular resolution over the region {75\circ}<{\ell}<{145\circ}, {-3.5\circ}<{b}<{5.5\circ}, using the Synthesis Telescope at the Dominion Radio Astrophysical Observatory. Small-scale structure, attributed to Faraday rotation effects, is detected over almost the entire survey area. In this paper we present images of a region in Cygnus, {83\circ}<{\ell}<{95\circ}.
A general framework for the interpretation of the observations is developed. The separate or combined effects of depth depolarization (differential Faraday dispersion) and beam depolarization do not allow the detection of polarized features that originate beyond a certain distance, which we refer to as the ``polarization horizon''. Its distance is frequency and beamwidth dependent, and varies with direction in the Galaxy. We determine this distance by examining results obtained in the direction of objects whose distances are known. In the region presented here, at {\ell}\approx{90\circ}, the polarization horizon is with a few kpc, probably confined within the Local arm.
Detailed results for a number of individual polarized features are also presented, including a supernova remnant, a strongly polarized feature associated with a molecular cloud, and a structure of extent {~2\circ in which the polarization structure is extremely smooth.
The Dominion Radio Astrophysical Observatory is a national facility operated by the National Research Council. The Canadian Galactic Plane Survey is a Canadian project with international partners, and is supported by the Natural Sciences and Engineering Research Council.