4672 Takuboku

4672 Takuboku, provisional designation 1988 HB, is a background asteroid from the outer regions of the asteroid belt, approximately 35 kilometers (22 miles) in diameter. It was discovered on 17 April 1988, by Japanese astronomers Seiji Ueda and Hiroshi Kaneda at the Kushiro Observatory on Hokkaido, Japan. The asteroid was named after the Japanese poet Takuboku Ishikawa.^[1] In 2005, measurement of the body's occultation ellipse also gave 35.0 × 35.0 kilometers.^[4]

4672 Takuboku

Discovery[1]
Discovered by	S. Ueda H. Kaneda
Discovery site	Kushiro Obs.
Discovery date	17 April 1988
Designations
MPC designation	(4672) Takuboku
Named after	Takuboku Ishikawa[1] (Japanese poet)
Alternative designations	1988 HB · 1971 HT 1979 WS7 · 1981 AN3
Minor planet category	main-belt[1][2] · (outer) background[3]
Orbital characteristics[2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc	46.11 yr (16,841 d)
Aphelion	3.3411 AU
Perihelion	3.0318 AU
Semi-major axis	3.1864 AU
Eccentricity	0.0485
Orbital period (sidereal)	5.69 yr (2,078 d)
Mean anomaly	45.665°
Mean motion	0° 10m 23.88s / day
Inclination	15.530°
Longitude of ascending node	91.663°
Argument of perihelion	175.66°
Physical characteristics
Dimensions	35.0 km × 35.0 km (occultation)[4]
Mean diameter	28.115±0.258 km[5] 35.59±1.9[6]
Geometric albedo	0.0609±0.007[6] 0.108±0.018[5]
Absolute magnitude (H)	10.90[6] 11.4[2]

Orbit and classification

Takuboku is a non-family asteroid from the main belt's background population.^[3] It orbits the Sun in the outer main-belt at a distance of 3.0–3.3 AU once every 5 years and 8 months (2,078 days; semi-major axis of 3.19 AU). Its orbit has an eccentricity of 0.05 and an inclination of 16° with respect to the ecliptic.^[2]

The body's observation arc begins with its first observation as 1971 HT at Crimea–Nauchnij in April 1971, or 17 years prior to its official discovery observation at Kushiro.^[1]

Physical characteristics

Takuboku has an absolute magnitude of between 10.90 and 11.4. As of 2018, no rotational lightcurve of Takuboku has been obtained from photometric observations. The body's rotation period, pole and shape remain unknown.^[2]

Diameter and albedo

According to the surveys carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer and the Infrared Astronomical Satellite IRAS, Takuboku measures 28.115 and 35.59 kilometers in diameter and its surface has an albedo of 0.108 and 0.0609, respectively.^[5][6]

Occultation

On 13 June 2005, Takuboku occulted 9.3 magnitude star TYC 0312-00789-1, causing a predicted magnitude drop 6.8 during 4.3 seconds. The occultation was visible over the southern island of New Zealand only. Measurement of the asteroid's occultation dimensions was 35.0 × 35.0 km for its major and minor best-fit ellipse (the fit's quality code is 1).^[4][a]

Naming

This minor planet was named after Japanese poet Takuboku Ishikawa (1886–1912) who lived in Japan's late Meiji-era. He is best known for Ichiaku no Suna (A Handful of Sand) a collection of 551 tanka poems published in 1910.^[1] The official naming citation was published by the Minor Planet Center on 10 November 1992 (M.P.C. 21131).^[7]

Notes

1. Occultation Prediction Chart: Occultation by (4672) Takuboku - TYC 0312-00789u on 13 June 2005, 11:51 UT