NED object is MESSIER 033; Reference is 1987A&AS...68..171B

   FIGURE 4.-Distribution of the linearly polarized emission at 17.4 cm in the
 field of M33 shown as contours in equal steps of 10 mJy per b.a. (1.5
 {sigma}). Bars indicate the orientations of the measured E-field; their
 lengths give the degree of polarization between P = 5% to 30% as described in
 the caption of figure 2. Positions of four possibly polarized point sources
 are marked.The coordinate grid is the same in all maps and refers to right
 ascension and declination of 1950.0. The optical centre at {alpha}_50_ =
 1h31m01.67s and {delta}_50_ = 30deg24'15.0" (de Vaucouleurs and Leach, 1981)
 is marked by << + >> in all figures.