(top) 3D scatter plot of the velocity observations. The spax- els along the edge of the shell shows noticeable excursions in velocity, as well as a "swimming ring-like" feature. (middle) Pixels used in the MCMC procedure (green) and those masked out (red) because the derived value of V_los differs notably for an expanding spheroidal shell. The center used is located at position (0,0) as marked with a white cross. (bottom) 3D scatter plot of the velocity observations once the mask is applied (grey dots). The remaining data points resemble a spheroidal- like structure.