It was discovered on 16 May 1990, by Japanese amateur astronomers Kin Endate and Kazuro Watanabe at the Kitami Observatory in eastern Hokkaidō, Japan.
[1] This minor planet was named after Ainonai, a small Japanese town located near Kitami in eastern Hokkaidō.
[10]: 23 In June 2008, a rotational lightcurve of Ainonai was obtained from photometric observations by James W. Brinsfield at the Via Capote Observatory (G69) in California.
Lightcurve analysis gave a rotation period of (38.31±0.05) hours with a brightness variation of (0.30±0.02) magnitude (U=3–).
[8] According to observations from the NEOWISE mission of NASA's space-based Wide-field Infrared Survey Explorer, Ainonai measures (10.920±0.122) kilometers in diameter and its surface has an albedo of (0.112±0.011).