Rectification of the ancient geographic coordinates in Ptolemy's Geographike Hyphegesis

Abstract. A multitude of the ancient places given by Ptolemy in his Geography (~150 AD) are so far unknown. One of the main problems of their identification are the errors of the given ancient coordinates. The different kinds of errors are illustrated by examples. A new geodetic-statistical analysis method is described, by which groups of places with homogeneous systematic errors and places with gross errors can be determined. Based on a transformation function describing the systematic errors, presumable modern coordinates of unknown places can be computed. That, in conjunction with further information, can make possible their identification. A test of the analysis method is carried out on a complex simulated example and shows its practicability. The analysis method has been applied within an interdisciplinary research project on Ptolemy's Geography. Further developments of the method are imaginable to make it accessible for related data diagnostics.