  A technique is described for the detection and measurement of close binary
systems whose images are unresolved. The method is based on analysis of the
moment of inertia tensor of the image, from which the product of the binary
flux ratio and square of the angular separation may be determined. Intrinsic
asymmetries of the point-spread function are removed by comparison with the
image of a reference star. Multiple exposures may be used to increase the
signal-to-noise ratio without need of image alignment. An example is given of a
simulated measurement of the dwarf carbon star system G77-61.
