4607 Seilandfarm
Rare L-type binary asteroid from the inner main belt.
4607 Seilandfarm (provisional designation 1987 WR) is a binary asteroid located in the inner main belt, measuring roughly 7 kilometers across. It is a rare L-type asteroid, reddish in color, and forms a binary system with a smaller moon.
The asteroid was discovered on 25 November 1987 by Japanese amateur astronomers Kin Endate and Kazuro Watanabe at Kitami Observatory on Hokkaidō. It was named after a dairy and cattle farm near Kitami, established in 1942 by Akio Seino and now run by four family members. The naming citation was published on 14 July 1992.
Seilandfarm orbits the Sun at a distance of 2.2 to 2.3 AU, completing one orbit every 3 years and 5 months (1,244 days). Its orbit has a low eccentricity of 0.02 and an inclination of 2° relative to the ecliptic. The first known observation of the asteroid was as 1951 CK1 at Abastuman Observatory in Georgia in February 1951, but the official discovery arc begins with the Kitami observation.
Photometric observations in February 2009 and September 2014 by Donald P. Pray and Petr Pravec at the Carbuncle and Ondřejov Observatories yielded a well-defined rotation period of about 3.968 hours, with a brightness variation of 0.15 to 0.17 magnitude, indicating a nearly spheroidal shape. During the 2009 observations, the asteroid was found to be a binary system. Its moon has an orbital period of 31.6 hours and, based on mutual eclipse and occultation events, is at least 29% the size of the primary, corresponding to a diameter of roughly 2 kilometers or more.
Size estimates from NEOWISE data range from 6.3 to 7.5 kilometers in diameter, with an albedo between 0.178 and 0.279. The Collaborative Asteroid Lightcurve Link assumes a standard stony albedo of 0.20, yielding a diameter of 7.1 kilometers, consistent with the space-based results.
Quick Facts
- Minorplanet
- yes
- Background
- #D6D6D6
- Discovered
- 25 November 1987
- Discoverer
- K. Endate / K. Watanabe
- Discovery Site
- Kitami Obs.
- Mpc Name
- (4607) Seilandfarm
- Named After
- Seilandfarm / (Japanese farm)
- Mp Category
- main-belt(inner)
- Epoch
- 4 September 2017 (JD 2458000.5)
- Uncertainty
- 0
- Observation Arc
- 42.23 yr (15,424 days)
- Aphelion
- 2.3083 AU
Facts from the source article.
Lore & Background
4607 Seilandfarm was discovered on 25 November 1987 by Japanese amateur astronomers Kin Endate and Kazuro Watanabe at Kitami Observatory on the Japanese island of Hokkaidō. It orbits the Sun in the inner main-belt at a distance of 2.2–2.3 AU every 3 years and 5 months, with an eccentricity of 0.02 and an inclination of 2°. The asteroid was first identified as 1951 CK1 at Abastuman Observatory in Georgia in February 1951, but its observation arc begins with the official discovery at Kitami.
On the SMASS taxonomic scheme, Seilandfarm is classified as a rare and reddish L-type asteroid. NEOWISE measurements give a diameter between 6.3 and 7.5 kilometers and an albedo between 0.178 and 0.279; the Collaborative Asteroid Lightcurve Link assumes a standard albedo of 0.20 and calculates a diameter of 7.1 kilometers. Rotational lightcurves obtained in February 2009 and September 2014 by Donald P. Pray and Petr Pravec at Carbuncle and Ondřejov Observatory, respectively, show a well-defined rotation period of 3.9681–3.9683 hours with a brightness variation of 0.15–0.17 magnitude, indicating a nearly spheroidal shape.
During the February 2009 photometric observations, it was discovered that Seilandfarm is a binary system. Its minor-planet moon has an orbital period of 31.6 hours. Based on mutual eclipse/occultation events, the satellite is thought to be at least 29% the size of the primary, translating to a diameter of approximately 2 kilometers or more.
Reader's Guide
The significance of 4607 Seilandfarm lies in its classification as a rare L-type asteroid and its status as a binary system. The discovery of its moon during photometric observations in February 2009 adds to the understanding of binary asteroid formation and dynamics in the inner main belt. The asteroid's well-defined rotation period and nearly spheroidal shape, determined from multiple lightcurves, provide constraints on its internal structure. The naming after a dairy and cattle farm near Kitami, Japan, reflects the tradition of honoring local landmarks associated with discovery sites. The asteroid's observation arc, extending back to a 1951 identification at Abastuman Observatory, illustrates the long-term tracking of minor planets. The NEOWISE and lightcurve data together offer a consistent diameter estimate around 7 kilometers, with the moon's size inferred from mutual events. This binary system contributes to the catalog of known asteroid satellites and aids in refining models of asteroid physical properties.
Frequently Asked Questions
What is 4607 Seilandfarm?
It is a binary asteroid residing in the inner main belt, roughly 7 kilometers in diameter, accompanied by a smaller moon orbiting the primary body.
Who discovered 4607 Seilandfarm and where?
Japanese amateur astronomers Kin Endate and Kazuro Watanabe first observed it on 25 November 1987 from Kitami Observatory on the island of Hokkaidō.
Why is it named Seilandfarm?
The name pays tribute to a dairy and cattle farm near Kitami, Hokkaidō, founded in 1942 by Akio Seino and still tended by four members of his family.
What makes 4607 Seilandfarm unusual among asteroids?
It belongs to the rare L-type spectral class, giving it a distinctly reddish appearance, and it exists as a binary system, which is uncommon for objects in the inner main belt.
How long does 4607 Seilandfarm take to orbit the Sun?
Its orbital period is approximately three years and five months, or about 1,244 days, as it circles the Sun from the inner main belt region.
More in Notable Asteroids, Part 3 1-24
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