To reduce the manual effort of assessing potential affected program parts during software evolution, we develop a tool, called Celadon, which automates the change impact analysis for AspectJ programs. Celadon is implemented in the context of the Eclipse environment and designed as a plugin. It analyzes the source code of two AspectJ software versions, and decomposes their differences into a set of atomic changes together with their dependence relationships. The analysis result is reported in terms of impacted program parts and affected tests. For each affected test, Celadon also identifies a subset of affecting changes that are responsible for the test's behavior change. In particular, as one of its applications, Celadon helps facilitate fault localization by isolating failure-inducing changes for one specific affected test from other irrelevant changes.