1583 Antilochus /ænˈtɪləkəs/ is a large Jupiter trojan from the Greek camp, approximately 108 kilometers (67 miles) in diameter.
It was discovered on 19 September 1950, by Belgian astronomer Sylvain Arend at Uccle Observatory in Belgium, and later named after the hero Antilochus from Greek mythology.
In December 2009 and June 2016, rotational lightcurves of Antilochus were obtained from photometric observations by American astronomer Robert Stephens at the Santana Observatory (646) and at the Center for Solar System Studies (CS3) in California.
[11][a] Stephen's period determination supersedes previously reported results by Vincenzo Zappalà (1985; 12 h), Federico Manzini (2007; 12 h) and René Roy (2009; 22.5 h) (U=3−/3).
[8][9][10] The Collaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an albedo of 0.0633 and a diameter of 101.62 kilometers, with Pravec's revised absolute magnitude of 8.59.