 Its V–I color index of 0.810 is also lower than that measured for most D-type Jupiter trojans (0.95).Several rotational lightcurves of "Diomedes" have been obtained from photometric observations since the 1960s.The so-far best-rated photometric observations by Robert Stephens at the Goat Mountain Astronomical Research Station and Santana Observatory in November 2008, gave a longer-than average rotation period of hours with a brightness variation of 0.34 magnitude ().