 In December 2009 and June 2016, rotational lightcurves of "Antilochus" were obtained from photometric observations by American astronomer Robert Stephens at the Santana Observatory and at the Center for Solar System Studies (CS3) in California.Lightcurve analysis gave a rotation period of 31.52 and 31.54 hours with an amplitude of 0.09 and 0.11 magnitude, respectively ().Follow-up observations over a total of 11 nights by Stephens in August 2017 gave the so-far best-rated lightcurve with a period of hours – which corresponds to half the period solution of the former results – and a slightly higher brightness variation of 0.12 magnitude ().