Fig. 5

Observed images, the 3-shape, and the ε-shape. a, c, e, and g Sample images in the cases where the Venus disk is large (1.01 μm, 2.02 μm, LIR, 283 nm) and b, d, f, and h the distributions of radial residuals of limb points from the ellipses. White dots in (a, c, e, and g) indicate detected limb points used for ellipse fitting. The argument of a vector from the ellipse center toward the positive direction of X is 0° and that of each limb point is measured anticlockwise in (b, d, f, and h). Solid lines are sixth-order polynomial functions obtained by fitting Eq. (4) to radial residuals of the limb points from the ellipse