Position angle (P.A.) of the GRB 171205A afterglow as a function of wavelength. Squared points indicate the observed P.A. at 90.5, 102.5, and 104.5 GHz. The upper limit at 92.5 GHz with a signal-to-noise ratio of 3 is also plotted with a red arrow. The gray dotted line indicates the constant fitting function with a reduced chi-square of 4.5 (d.o.f = 3).