to the median temperature because this threshold level divides the map into high and low regions of equal area. Unlike the genus with the temperature threshold level, the genus with the area fraction threshold level is less sensitive to the higher order information (e.g., skewness) coming from the one-point distribution (Vogeley et al. 1994). For each map we calculate area fraction threshold levels on a sphere with HEALPix format and with the same resolution as the stereographically projected map. This is because the stereographic mapping does not preserve the areas.

For a two-dimensional random phase Gaussian field, the genus has a form of $g(\nu) = A \nu e^{-\nu^2 /2}$ (Gott et al. 1990). The amplitude $A$ is normalised so that $g(\nu)$ is the genus per steradian. Non-Gaussian feature in the CMB anisotropy will appear as deviations of the genus curve from this relation. Non-Gaussianity can shift the observed genus curve to the left or right directions, and also alter the amplitudes of the genus curve at positive and negative levels differently, causing $|g(\nu \approx -1)| \ne |g(\nu \approx +1)|$. We define shifts at negative and positive threshold levels, $\Delta\nu_{-/+}$, with respect to the Gaussian relation by minimizing the $\chi^2$ between 