Astrometric orbit of a low-mass companion to an ultracool dwarf J. Sahlmann, P. F. Lazorenko, D. Ségransan, E. L. Martín, D. Queloz, M. Mayor and S. Udry A&A, 556 (2013) A133 Published online: 08 August 2013 DOI: 10.1051/0004-6361/201321871