Occultation Evidence for a Satellite of the Trojan Asteroid (911) Agamemno

As early as 1977, claims were made that asteroids probably had satellites, based on observations of occultations of stars by asteroids. But these early claims, mostly based on visual observations with no recordings of the event, were dismissed by most astronomers at the time....

....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 36cm telescope that shows a deep brief secondary occultation that is likely due to a satellite, of about 5 km (most likely 3 to 10 km) across, at 278 km ±5 km (0.0931′′) from the asteroid’s 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.....

[link to arxiv.org]