A precise and accurate determination of the cosmic microwave background temperature at z = 0.89 S. Muller, A. Beelen, J. H. Black, S. J. Curran, C. Horellou, S. Aalto, F. Combes, M. Guélin and C. Henkel A&A, 551 (2013) A109 Published online: 04 March 2013 DOI: 10.1051/0004-6361/201220613