Flattening and Gravity Harmonics of Uranus and Neptune Against Rotational Response

This paper examines the rotational flattening of the ice giants and what their gravity harmonics say about interior concentration. Using only published input values and transparent formulae, the calculation addresses whether the hydrostatic flattening predicted from the measured rotation rate and second gravity harmonic matches the observed oblateness of each planet, and what the ratio of J2 to the rotation parameter implies. The headline results are: rotation_parameter_q_uranus = 0.02886; rotation_parameter_q_neptune = 0.02563; hydrostatic_flattening_uranus = 0.0197. The method, inputs and limitations are stated in full so that any reader can reproduce or rescale every number from the deposited calculation script. The central finding is that the hydrostatic estimate reproduces the observed Uranian flattening closely and sits somewhat above the observed Neptunian value, a reminder that the observed shape also carries wind-driven dynamical contributions that a hydrostatic formula cannot capture. Agreement and disagreement with independent published estimates are reported at their actual size, and the conclusions are limited to what the budget arithmetic supports.