I have some noisy data (x-y coordinates) containing two distinct clusters of data. Each cluster is centred at an unknown point on the unit circle. How can I estimate these two points (green points in the diagram)? We can assume the noise is Gaussian and noise power is equal in x and y directions. Computational power is extremely limited, so I'm probably looking for a non-iterative approach involving as few 'complicated' operations (e.g. square roots) as possible.