Interstellar polarization in the dust lane of Centaurus A (NGC 5128)

Optical and infrared linear polarization measurements of the Type 1 supernova 1986G in Centaurus A are used to determine the wavelength dependence of polarization produced by transmission of radiation through the dust lane of the galaxy. The observations are consistent with the standard form of interstellar polarization used in our Galaxy with values of Pmax= (5.16±0.04) per cent and λmax= (0.43±0.01)μm, with foreground material in our Galaxy contributing no more than ≡0.5 per cent to the observed polarization. The efficiency of alignment of the grains in Cen A is smaller than found in the Milky Way.