Satellite image registration has been investigated for several years. Nevertheless, little attention has been paid to the linear geometry of the satellite's imaging sensor, often consisting of several pushbroom cameras. Each pushbroom camera cap- tures 1-D image and uses straight motion of the satellite to build a 2-D image. Yet, attitude variations of the satellite dur- ing the aquisition process can lead to significant distortions in the 2-D image. In this paper, we expose the problem and present a constrained image registration method to estimate the satellite's attitude variations, and thus correct the distorted images. We use a Lucas Kanade framework and a piecewise polynomial model under constraints to deduce the registra- tion equation. The performances of our algorithm are shown on two satellite datasets.