Noise considerations in stellar speckle interferometry*†

Abstract

A general model for the signal-to-noise ratio for stellar speckle interferometry is developed, including the effects of finite sample averaging, quantum fluctuations, and additive noise. We find that in most cases the controlling parameter is the ratio of the total spatial spectrum to the signal spatial spectrum. Provided the average number of photo events per frame is greater than one, the signal-to-noise ratio for an ideal quantum limited detector is insensitive to aperture size. If a signal-independent noise source is also present, either source can dominate under certain conditions. Large resolved objects must be considerably brighter than their equivalent point source if diffraction details are to be observed.