OGLE-2005-BLG-390Lb's signature was first detected on August 10, 2005 by observations at the Danish 1.54-m telescope at ESO La Silla Observatory in Chile. The telescope was part of a network of telescopes used by the PLANET/RoboNet gravitational microlensing campaign. Much of the follow-up observational data was gathered by a 0.6-m telescope at the Perth Observatory in Western Australia. The paper submitted to Nature bears the names of all members of PLANET, RoboNet, OGLE, and MOA.