 It showed a periodicity of hours, during which time the brightness of "Hirayama" varies by in magnitude ().At the same time, photometric observations by astronomers Roberto Crippa and Federico Manzini gave a rotation period of 22.37 hours and a brightness variation of 0.47 magnitude ().These results supersede an observation from January 2005, by Hiromi and Hiroko Hamanowa at their Hamanowa Astronomical Observatory, Japan, that gave a shorter period of 13.59 hours with an amplitude of 0.57 magnitude.