Stokes I (top left), Stokes Q (bottom left), and Stokes U (bottom right) images for a representative mosaic centered on the Perseus molecular cloud, alongside an extinction map (top right; J. Kainulainen et al. 2009) of the same region. The Stokes I panel highlights compact and diffuse radio continuum sources, while the extinction map traces the underlying dust structure of the molecular cloud. Blank pixels in the extinction map correspond to regions where stellar measurements were excluded to minimize bias from foreground stars and stars embedded within the cloud, as well as from sources rejected through an iterative sigma-clipping procedure at the 5σ level relative to the local extinction field. The large-scale fluctuations in Stokes Q and U arise from diffuse Galactic synchrotron emission, whose polarization structure is further modified by Faraday rotation in the intervening magneto-ionic medium.