NED object is 3C 020; Reference is 1981MNRAS.195..261L

   Figs 41 - 58 show maps in which the lengths of the vectors are proportional
 to percentage polarization at the frequency of observation and their
 directions are those of the apparent magnetic field (corrected to infinite
 frequency using the rotation measure given in Table 10). The vectors are
 superimposed on contours of total intensity, I. The maps should give a good im
 pression of the direction and degree of ordering of the magnetic field.
 Vectors are only plotted where the total intensity exceeds some limiting
 value, so that their magnitudes and directions are reliably determined. Figs
 41 - 58 will be referred to as 'magnetic-field maps'.