Polarized standard star HD 43384 observed with CAFOS at two epochs, on 2015-04-29 at 20:14 UT (green line) and 21:14 UT (blue line). The two epochs are consistent with each other with an RMS of ~0.04%. The red dashed lines in the polarization panel indicate p_max and λ_max and their errors (dotted line) determined by Hsu & Breger (1982), and the red dots are their individual measurements. The red dots in the χ − χ₀(V) panel indicate the phase retardance variance determined in Patat & Taubenberger (2011).