Venter, Christo; Vorster, Michael Johannes; Büsching, Ingo; De Jager, Ocker Cornelis
(IOP Publishing, 2011)
Observations of the globular clusters (GCs) NGC 6388 and M15 were carried out by the High Energy Stereoscopic System array of Cherenkov telescopes for a live time of 27.2 and 15.2 hr, respectively. No gamma-ray signal is ...