Abstract
Concentric projection theory and an adjustment by means of third-degree polynomials are used to analyze the transformations relating celestial equatorial coordinates to rectangular coordinates, measured on a plate obtained by means of a Schmidt telescope lacking an objective prism. The results obtained show the presence of distortions probably due to photographic emulsion random defects. Systematic defects in the reference catalog, and/or anomalous atmospheric refraction and filter effects. It is found that the mean radiation detected in the actual position of any stellar image reaches a value of 0.64 arcsec within a circular plate zone of approximately one deg radius.
