Detection of parity of a binary star in triple correlation speckle interferometry. I. Signal-to-noise ratio

Karbelkar and Nityananda (1987) rectified, in the wave limit (high flux), an earlier overestimate of SNR for the bispectrum of a speckle image. The relevance of this work to the opposite case of low photon levels is pointed out. For the specific case of binary stars, SNR calculations are presented for the detection of the parity (the side of the brighter component) of the binary. Parity, defined as a special case of the focal-plane triple correlation, is shown to have significantly poorer limiting faintness than that found in the autocorrelation case. The simplified nature of the object and speckle model allow a rather complete study of the noise properties of triple correlation analysis, which should be useful in more complex situations. 14 refs