Ratios of the median Hα fluxes between the southern, central, and northern fiducial regions of IC 1553, as defined in Sect. 4.5, as a function of the height above the midplane in the northwestern direction (where z < 0). The blue data points give the south-to-center flux ratio and the orange data points give the south-to-north ratio. The dashed line marks the ordinate value of 1.