Correlations of polarization components in the coordinate frame are a natural basis for searches of parity-violating modes in the Cosmic Microwave Background (CMB). This fact can be exploited to build estimators of parity-violating modes that are {sl local} and robust with respect to partial-sky coverage or inhomogeneous weighting. As an example application of a method based on these ideas we develop a peak stacking tool that isolates the signature of parity-violating modes. We apply the tool to {sl Planck} maps and obtain a constraint on the monopole of the polarization rotation angle $alpha < 0.72$ degrees at $95%$ We also demonstrate how the tool can be used as a local method for reconstructing maps of direction dependent rotation $alpha(hat {n})$.
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