sentence1: even if a gaussian is a good approximation to the shape of strong absorption features , we do not expect that line-fitting can yield unique fits .
sentence2: as a gaussian is a sufficient model for a symmetric psf caused by atmospheric smearing , and spin one through three distortions will most severely affect the lensing measurement , we choose a functional form consisting of a gaussian plus spin one through three gaussian perturbations which satisfies the above listed second and third moment constraints .