Abstract
The Diffracto-Astrometry technique arises as a continuation of the work done by Allen et al. (1974, 2004) about the internal motions of Trapezium-type systems. Applying this technique to a 12 year period (1995-2007) Orion Trapezium images from the public database of the Hubble Space Telescope (HST) Wide Filed Planetary Camera 2 (WFPC2), it is possible to obtain high precision astrometric results (Sánchez et al. 2008). Thus we add new measurements to the historic data compilation (1832-2007) and determine relative motions and transversal velocities for some Trapezium components.
