3240 Laocoon

3240 Laocoon is a carbonaceous Jupiter trojan from the Trojan camp, approximately 51 km in diameter. It was discovered on 7 November 1978, by American astronomers Eleanor Helin and Schelte Bus at Palomar Observatory in California. The D-type asteroid belongs to the 100 largest Jupiter trojans and has a rotation period of 11.3 hours. It was named after Laocoön from Greek mythology.

Classification and orbit
Laocoon resides in the Trojan camp of Jupiter's Lagrangian point, which lies 60° behind the gas giant's orbit. It is also a non-family asteroid of the Jovian background population.

It orbits the Sun at a distance of 4.6–5.9 AU once every 11 years and 12 months (4,375 days; semi-major axis of 5.23 AU). Its orbit has an eccentricity of 0.13 and an inclination of 2° with respect to the ecliptic. The asteroid was first observed as  at Crimea–Nauchnij in September 1976, extending the body's observation arc by 2 years prior to its official discovery at Palomar.

Physical characteristics
Laocoon has been characterized as a D-type asteroid by Pan-STARRS' survey and in the SDSS-based taxonomy. It has a V–I color index of 0.88.

Lightcurve
In April 1996, Laocoon was observed by Italian astronomer Stefano Mottola using the now decommissioned Bochum 0.61-metre Telescope at ESO's La Silla Observatory in Chile. The lightcurve gave a rotation period of $51.69 km$ hours with a brightness variation of $11.312 h$ in magnitude.

Diameter and albedo
According to the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, the Jovian asteroid measures 51.7 kilometers in diameter and its surface has an albedo of 0.060, while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for a carbonaceous asteroid of 0.057 and calculates a diameter of 50.8 kilometers with an absolute magnitude of 10.2.

Naming
This minor planet was named after the Troyan priest Laocoön from Greek mythology. He and both his sons were killed by serpents sent by the gods because he tried to expose the Greek's deception of the Trojan Horse. The official naming citation was published by the Minor Planet Center on 7 September 1987 (M.P.C. 12210).