David M Goldberg

We introduce the octopole moment measurement of the light distribution in galaxies as a probe of the weak lensing shear field. While traditional ellipticity estimates of local shear have traditionally been limited by the width of the background intrinsic ellipticity distribution, the dispersion in the intrinsic octopole distribution is expected to be quite small, meaning that the signal is ultimately limited by measurement noise, not by intrinsic scatter. In a series of estimates, we show that current observations are at the regime where the octopole estimates will be able to contribute to the overall accuracy of the estimates of local shear fields.