Abstract
In this paper we present the evaluations of the astrometric reduction of CFHT images that are intended to be used for the construction of a deep ecliptic catalogue, using UCAC3 as reference catalogue. We find that the average centering error for star-like objects is 0.012 pixel (2.2 mas), but for extended objects it is 0.037 pixel (6.9 mas). By comparing measurements with two different filters a strong chromatic aberration was detected, that was modeled and corrected. After that correction the differences between instrumental coordinates in both filters are (-7±11) mas in X and (-1±12) mas in Y and no systematic pattern is apparent. The differences between celestial coordinates obtained with the two filters are 15 mas in α cos(δ) and 26 mas in δ.
