It was discovered on 14 February 1991, by Japanese astronomers Kin Endate and Kazuro Watanabe at the Kitami Observatory on the island of Hokkaidō in northern Japan.
[13] It orbits the Sun in the inner asteroid belt at a distance of 2.1–2.7 AU once every 3 years and 9 months (1,358 days).
It was taken at Palomar Observatory in March 1950, almost 41 years prior to the asteroid's official discovery observation at Kitami in 1991.
During the photometric observation by Warner and Coley in January 2013 (see above), mutual occultation and eclipsing events revealed that Shumarinaiko is a synchronous binary asteroid with an elongated minor-planet moon in orbit.
According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Shumarinaiko measures 5.253 kilometers in diameter and its surface has an albedo of 0.306,[7][8] while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 5.66 kilometers based on an absolute magnitude of 13.6.