Retraction to: Hybrid Attitude Coordination Controller for Multiple-Spacecraft Systems with Hyperbolic-Tangent Distributed Observer (Journal of Guidance, Control, and Dynamics)

Retraction Notice Based on a detailed investigation of this article [https://dx.doi.org/10.2514/1.G003508], it is apparent that significant portions are not original contributions of the authors but rather plagiarize the following previously published works: Gui, H., and de Ruiter, A. H. J., “Global Finite-Time Attitude Consensus of Leader-Following Spacecraft Systems Based on Distributed Observers,” Automatica, Vol. 91, May 2018, pp. 225–232, and Gui, H., and Vukovich, G., “Global Finite-Time Attitude Tracking via Quaternion Feedback,” Systems and Control Letters, Vol. 97, 2016, pp. 176–183. Portions of a preprint version of the article published in Automatica also were plagiarized, arxiv:1707.08076v2. This retraction has been initiated by the publisher.