In the last ten years, finding communities in networks, has been the subject of intense studies. If modularity maximization is still one of the mostly studied criterion, some criticism tend to arise and researchers in that field are more and more studying various criterion for finding communities in networks. To facilitate the task of studying various or new criterion, Constellation was developed. The software does not only allow an interactive definition of new criterion, it also provides a graphical interface and an optimization module that are useful tools for the researcher. This paper describes Constellation and its use.