Sympathetic to a negotiated peace with the Greeks, he advised his countrymen to return Helen of Troy to Menelaus during the Trojan War.
[4][17] The first rotational lightcurves of Antenor were obtained from photometric observations in October 1989, by astronomers Mario Di Martino and Maria Gonano–Beurer with the now decommissioned ESO 1-metre telescope at La Silla in Chile.
[15][16] In April 1969, a follow-up observation by Mottola gave the so-far best-rated rotation period of in 7.965 hours with a brightness variation of 0.09 magnitude (U=2+).
[5][15] In September 2012, by astronomers at the Palomar Transient Factory derived two concurring period of 7.960 7.964 hours with an amplitude of 0.12 and 0.15 in the R- and S-band respectively (U=2/2).
[5][13] Between 2016 and 2018, observation by Robert Stephens at the Center for Solar System Studies, California, gave rotation period of 7.906, 7.964 hours with an amplitude of 0.09 (U=2+/2+/n.a.).
[12][14][a] In October 2018, Stephens, in collaboration with Brian Warner (716) and several other European observers including Amadeo Aznarand (Z95)/(J42) and Vladimir Benishek at Belgrade Observatory, reported that Antenor is likely a binary system.