Left: average Faraday rotation measures RM between λ3.5 cm and λ6.2 cm (VLA only) at 25′′ resolution along a half ring between 3′–4′ radius in the sky plane, with its centre at RA, Dec (J2000) = , +68° 06′ 07′′ (offset from the galaxy’s centre), which best delineates the inner spiral arm from north-west to south-east. The position angle along the ring starts at −65° and runs counter-clockwise (0° is north and 90° is east). An interval in position angle of 50° corresponds to 3′ (3 kpc) along the ring. Right: average polarized intensity at λ6.2 cm (VLA only) at 25′′ resolution in the same half ring.