Photoelectric Astrometry - a Comparison of Methods for Precise Image Location

Published in Modern Astrometry, Proceedings of IAU Colloq. 48, held in Vienna, Austria, 11-14 September, 1978. Edited by F. V. Prochazha and R. H. Tucker. Vienna University Observatory, 1978, p.197

https://ui.adsabs.harvard.edu/abs/1978moas.coll..197L/abstract

Abstract: The paper describes several techniques for obtaining the precise location of a noisy image such as a star, spectral line, or solar limb by means of characteristic 'weighing functions'. The imprecision of an image location estimate can be expressed in terms of the weighting function, the image shape, and noise covariance. It is limited by the intrinsic imprecision of the image attained with an optimum weighting function, computable from the image characteristics. The hypothetical optimum method is compared with commonly used location methods, such as computing the median or center of gravity, and least-squares fitting and cross-correlating. One- and two-dimensional Gaussian images are considered along with diffraction and seeing images; the results also apply to photographic astrometry, measurement of radial velocities, and timing of pulses.