Detailed study of the X-ray and optical/UV orbital ephemeris of X1822–371 R. Iaria, T. Di Salvo, L. Burderi, A. D’Aí, A. Papitto, A. Riggio and N. R. Robba A&A, 534 (2011) A85 Published online: 07 October 2011 DOI: 10.1051/0004-6361/201117334