Table 1.

Results for angles characterizing the orientation in space of the c axis for the data shown in Fig. 2

Location and color of pixel	Ao	Bo	γ	χ
h = 149, v = 882 green	64	95	1°	90°
	A	B	γ	χ
h = 251, v = 407 red	74	80	23°	67°
h = 335, v = 569 blue	67	84	43°	70°
h = 495, v = 856 magenta	65	70	43°	59°

A, B, and γ result directly as the best-fit parameters obtained from fitting the experimental data to A + B cos² (EPU°-γ). Simple geometry implies that B = B_o sin²χ. The known orientation yields the value for B_o (first row of this table) thus χ can be calculated, assuming that A has a constant value and specifically that A_o = A, which is reasonable within the experimental errors. The errors (estimated by comparing the results for unconstrained fits and fits in which the parameter A is constrained to be the same for all the curves) are approximately 3° for γ and approximately 10° for χ.