Measurement of r 0 with speckle interferometry

Stellar speckle interferometry of unresolved objects yields the short-exposure lens–atmosphere MTF. Using Korff’s calculations, a value of the wave correlation scale r0 can be obtained from the MTF. We demonstrate this, and also show how the power spectra can be corrected so that r0 values can be extracted from resolvable object data. Assuming the validity of Korff’s calculations for speckle interferometry, unresolved and resolved object data can be then used to test calculations for short-and long-exposure imaging. Tests with field data show only a weak distinction in speckle interferometry between short- and long-exposure imaging. A Gaussian image shape does not agree with the data.