Model Fitting

To obtain the proper zodiacal cloud model, we compare to the brightness distribution /(A — A0) calculated along the line of sight. That is, where the modified fan model is applied for the number density of zodiacal cloud N(r, () [9] and for the scattering phase function defined in [10]. a = 1.2 is assumed for the density power-law exponent. To avoid the edge effect derived from Fourier-filtering, the region of 55° < A - A0 < 115° and -20° < (3 < 20° are gridironed by 5° x 5° and the data at each crosspoint are used in the model fitting. The total of 111 data points are available. The eight variables are required for fitting the parameters in the models, i.e. i, fl, a level of bias, scaling factor(C), three shape parameters(/3',7,/i) for the modified fan model, and the intensity of airglow emission at the zenith IAg{z = 0). We have determined such eight parameters by the simplex method so as to minimize the difference between our photometric data and the calculated brightness. The followings are the values of parameters of interest obtained here. That is, i = 2°.2, Q = 53°, ¡3' = 4.62, 7 = 0.937, fi = 0.216 and IAG{z = 0) = 41 Sio®.

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