To understand a certain issue of the system we want to ask the knowledgeable developers. Yet, in large systems, not every developer is knowledgeable in all the details of the system. Thus, we would want to know which developer is knowledgeable in the issue at hand. In this paper we present the Chronia tool that implements the Ownership Map visu- alization to understand when and how different developers interacted in which way and in which part of the system. circle reflects the size of the change, and the color of the line denotes the author who owns most of the lines of code of the file in that period. File A commit by the green author followed by the ownership file removed by the blue author file present from the first import