TASTE II. A new observational study of transit time variations in HAT-P-13b V. Nascimbeni, G. Piotto, L. R. Bedin, M. Damasso, L. Malavolta and L. Borsato A&A, 532 (2011) A24 Published online: 14 July 2011 DOI: 10.1051/0004-6361/201116830