911 Agamemnon, provisional designation 1919 FD, is a large Jupiter trojan and a suspected binary asteroid from the Greek camp, approximately 168 kilometers (100 miles) in diameter.

[19] It has also been characterized as a D-type in both the Tholen- and SMASS-like taxonomy of the Small Solar System Objects Spectroscopic Survey (S3OS2).

[19][18] Photometric observations of this asteroid during 1997 were used to build a lightcurve showing a rotation period of 6.5819±0.0007 hours with a brightness variation of 0.29±0.01 magnitude.

[5][14] According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Agamemnon measures between 131.04 and 185.30 kilometers in diameter, based on a common absolute magnitude of 7.89 and a surface albedo between 0.037 and 0.072.

[9] The Collaborative Asteroid Lightcurve Link agrees with the results obtained by IRAS, that is, an albedo of 0.0444 and a diameter of 166.66 kilometers based on an absolute magnitude of 7.89.