The Open Cirrus project aims to provide a federated cloud computing testbed for systems and applications research. It consists of several geographically distributed data centers that researchers can access through a single sign-on. This will allow researchers to study issues around leveraging multiple data centers and conduct large-scale experiments not possible on individual clusters. The goals are to foster innovation in cloud computing systems research, encourage new cloud applications research, collect experimental datasets, and develop open-source cloud software stacks. By federating existing resources from different organizations into a single testbed, Open Cirrus hopes to reduce costs through shared innovation while increasing impact through a larger collaborative effort.