5481 Kiuchi
Bright binary Vestian asteroid with a synchronous moon.
5481 Kiuchi (provisional designation 1990 CH) is a bright asteroid from the inner asteroid belt, roughly 4 kilometers across. It belongs to the Vesta family and is a binary system, meaning it has a small moon. The asteroid was discovered on 15 February 1990 by Japanese astronomers Kin Endate and Kazuro Watanabe at Kitami Observatory in Hokkaidō, Japan. It was named after their colleague Tsuruhiko Kiuchi, an amateur astronomer who rediscovered the lost comet Swift–Tuttle in 1992 using only binoculars, following a prediction by Brian Marsden. The naming citation was published on 1 September 1993.
Kiuchi orbits the Sun in the inner main-belt at a distance of 2.2 to 2.5 AU, completing one orbit every 3 years and 7 months (1,307 days). Its orbit has a low eccentricity of 0.06 and an inclination of 6° relative to the ecliptic. The asteroid was first observed as 1970 SR at Crimea–Nauchnij in 1970, extending its observation arc by 20 years before its official discovery.
In March 2008, photometric observations by a team of astronomers at several observatories—including Ondřejov Observatory in the Czech Republic, Leura Observatory in Australia, Goat Mountain in California, Skalnaté pleso Observatory in Slovakia, and McDonald Observatory in Texas—revealed that Kiuchi is a synchronous binary asteroid. Its moon orbits every 20.90 hours, based on mutual eclipsing and occultation events. The satellite is about one-third the diameter of the primary, roughly 1.3 kilometers across (secondary-to-primary mean-diameter ratio of 0.33±0.02).
Kiuchi itself is a bright V-type asteroid, as determined by the PanSTARRS survey. The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.40 and calculates a diameter of 3.86 kilometers from an absolute magnitude of 13.676 (based on revised WISE data). The primary has a rotation period of 3.6196±0.0002 hours, with a small brightness variation of 0.1 magnitude, suggesting a nearly spheroidal shape. Follow-up observations by Petr Pravec in 2013 and 2016 confirmed these results, giving rotation periods of 3.6198 and 3.6196 hours, with amplitudes of 0.08 and 0.1 magnitude, and satellite orbital periods of 20.9 and 20.9062 hours, respectively.
Quick Facts
- Minorplanet
- yes
- Background
- #D6D6D6
- Discovered
- 15 February 1990
- Discoverer
- K. Endate / K. Watanabe
- Discovery Site
- Kitami Obs.
- Mpc Name
- (5481) Kiuchi
- Named After
- Tsuruhiko Kiuchi / (Japanese amateur astronomer)
- Mp Category
- main-beltVesta
- Epoch
- 4 September 2017 (JD 2458000.5)
- Uncertainty
- 0
- Observation Arc
- 46.14 yr (16,851 days)
- Aphelion
- 2.4858 AU
Facts from the source article.
Lore & Background
5481 Kiuchi is a bright core member of the Vesta family, one of the main-belt's largest families. It orbits the Sun in the inner main-belt at a distance of 2.2–2.5 AU once every 3 years and 7 months, with an eccentricity of 0.06 and an inclination of 6°. It was first identified as 1970 SR at Crimea–Nauchnij in 1970, extending the body's observation arc by 20 years prior to its official discovery at Kitami.
The asteroid was named in honor of Japanese amateur astronomer Tsuruhiko Kiuchi, known for the rediscovery of the periodic Perseid Comet Swift–Tuttle in 1992 using only binoculars, based on a prediction by Brian Marsden. The naming citation was published on 1 September 1993.
In March 2008, photometric observations by astronomers at Ondřejov Observatory, Leura Observatory, Goat Mountain, Skalnaté pleso Observatory, and McDonald Observatory revealed that Kiuchi is a synchronous binary asteroid with a minor-planet moon orbiting every 20.90 hours. The satellite's diameter is about 1.3 kilometers, with a secondary-to-primary mean-diameter ratio of 0.33±0.02.
Reader's Guide
5481 Kiuchi is significant as a binary asteroid within the Vesta family, providing insights into the formation and evolution of small bodies in the inner asteroid belt. Its synchronous binary nature, discovered through photometric observations in 2008, allows study of mutual eclipsing and occultation events. The asteroid's nearly spheroidal shape, indicated by a small brightness variation of 0.1 magnitude, and its rotation period of 3.6196 hours have been confirmed by multiple follow-up observations. The naming honors Tsuruhiko Kiuchi's notable rediscovery of a lost comet using binoculars, highlighting the contributions of amateur astronomers. The asteroid's bright V-type spectrum and high albedo (assumed 0.40) make it a well-characterized member of its family. Its legacy includes serving as a target for binary asteroid studies and as a reminder of the role of citizen scientists in astronomy.
Did You Know?
- 5481 Kiuchi is a synchronous binary asteroid with a moon about 1.3 km in diameter.
- The asteroid is named after amateur astronomer Tsuruhiko Kiuchi, who rediscovered the lost comet Swift–Tuttle using binoculars.
- Its rotation period is 3.6196 hours with a brightness variation of only 0.1 magnitude, indicating a nearly spheroidal shape.
More in Notable Asteroids, Part 3 1-24
Spotted an error? Know more?
Reader corrections go straight into our review queue. Suggest an edit · How this site is sourced