The Transfer Function, Signal-to-Noise Ratio, and Limiting Magnitude in Stellar Speckle Interferometry

Abstract

Recent theoretical work has shown that atmospheric seeing which would be regarded as poor for conventional imaging is desirable for attaining diffraction-limited resolution from an aberrated telescope using speckle interferometry. This result is discussed and illustrated with computational examples. An expression is derived for the overall signal-to-noise ratio in speckle interferometry. The signal-to-noise decreases as the seeing deteriorates; in practice therefore the optimum form of seeing for speckle interferometry depends in a complicated manner on the desired signal-to-noise ratio at a specified spatial frequency and on the telescope aberration. It is also shown that binary stars of magnitude |$m_\text v\simeq16$| should be detectable in reasonable observing times using realistic detection parameters.