Left: total intensity Stokes I map at 850 µm observed with the JCMT SCUBA-2/POL-2 towards W3(OH) in units of mJy beam⁻¹. The contours are I = 30, 100, 500, 1000, and 5000 mJybeam⁻¹. The lowest contour of I = 30 mJybeam⁻¹ is equivalent to I/δI ~ 13. The red lines show the orientation of the POS B-field angle (${\chi }_{B_{\text{POS}}}$) for I/δI > 5, PI/δPI > 1, and PF < 25%. The lengths of the red lines are proportional to PF. A line showing PF = 10% is indicated on the plot. The data are at an angular resolution of 14″ or ~0.14 pc at the 2 kpc distance of the source. Right: contours and red lines are the same as in the left panel. The red lines are plotted with the same length to better show the B-field orientation. The background is a colour image composed using Spitzer 3.6 µm, 4.5 µm, and 8.0 µm images for the blue, green, and red, respectively.