A Technique for Photometric Detection and Measurement of Unresolved Binary Systems

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.