Occultation evidence for a satellite of the Trojan asteroid (911) Agamemnon

On 2012 January 19, observers in the northeastern United States of America observed an occultation of 8.0-mag HIP 41337 star by the Jupiter–Trojan (911) Agamemnon, including one video recorded with a 36 cm telescope that shows a deep brief secondary occultation that is likely due to a satellite, of about 5 km (most likely 3–10 km) across, at 278±5 km (0.0931″) from the asteroidʹs center as projected in the plane of the sky. A satellite this small and this close to the asteroid could not be resolved in the available VLT adaptive optics observations of Agamemnon recorded in 2003. The outline of Agamemnon is fit well by an ellipse with dimensions 190.6±0.9 km by 143.8±1.5 km. The angular diameter of HIP 41337 was found to be 0.5±0.1 milli-arcsec. After (624) Hektor, this could be the second Jupiter Trojan asteroid known to possess a small satellite.