It was discovered on 2 February 1989, by Japanese amateur astronomers Masaru Arai and Hiroshi Mori at the Yorii Observatory in Japan.
[1] Hiromiyuki is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements.
[1] Hiromiyuki is an assumed S-type asteroid based on its classification into the Flora family.
[5] In February 2007, a rotational lightcurve of Hiromiyuki was obtained from photometric observations by Donald P. Pray at Carbuncle Hill Observatory (912), in collaboration with Adrián Galád, Marek Husárik, and Julian Oey.
Lightcurve analysis gave a rotation period of 6.828 hours with an exceptionally high brightness amplitude of 1.00±0.02 magnitude (U=3), which typically indicates that the body has an elongated shape.