HESS upper limit on the very high energy y-ray emission from the globular cluster 47 Tucanae - Aharonian, F.; Akhperjanian, A.; Anton, G.; Barres de Almeida, U.; Bazer-Bachi, A.; Becherini, Y.; Behera, B.; Bernlöhr, K.; Boisson, C.; Bochow, A.; Borrel, V.; Braun, I.; et al. (EDP Sciences, 2009)