| Minorplanet: | yes |
| 7776 Takeishi | |
| Background: |
|
| Discovery Ref: |   |
| Discoverer: | T. Urata |
| Discovery Site: | Nihondaira Obs. |
| Discovered: | 20 January 1993 |
| Mpc Name: | (7776) Takeishi |
| Alt Names: | 1993 BF1981 RJ |
| Named After: | Masanori Takeishi  (Japanese astronomer) |
| Mp Category: | background  |
| Orbit Ref: |   |
| Epoch: | 23 March 2018 (JD 2458200.5) |
| Uncertainty: | 0 |
| Observation Arc: | 35.66 yr (13,023 d) |
| Aphelion: | 2.6137 AU |
| Perihelion: | 1.9042 AU |
| Semimajor: | 2.2590 AU |
| Eccentricity: | 0.1571 |
| Period: | 3.40 yr (1,240 d) |
| Mean Anomaly: | 258.36° |
| Mean Motion: | / day |
| Inclination: | 9.4908° |
| Asc Node: | 309.46° |
| Arg Peri: | 39.968° |
| Mean Diameter: | (calculated) |
| Rotation: | |
| Albedo: | (assumed) |
| Spectral Type: | S (assumed) |
| Abs Magnitude: | 12.8 13.0 13.34 |
7776 Takeishi, provisional designation, is a background asteroid from the inner regions of the asteroid belt, approximately 6km (04miles) in diameter. It was discovered on 20 January 1993, by Japanese astronomer Takeshi Urata at the Nihondaira Observatory in Japan. The assumed S-type asteroid has a rotation period of 8.9 hours. It was named after Japanese amateur astronomer Masanori Takeishi.
Takeishi is a non-family asteroid from the main belt's background population. It orbits the Sun in the inner asteroid belt at a distance of 1.9–2.6 AU once every 3 years and 5 months (1,240 days; semi-major axis of 2.26 AU). Its orbit has an eccentricity of 0.16 and an inclination of 9° with respect to the ecliptic. The body's observation arc begins with first observations as at Anderson Mesa Station in September 1981, more than 11 years prior to its official discovery observation.
Takeishi is an assumed, stony S-type asteroid.
Two rotational lightcurves of Takeishi have been obtained from photometric observations by French amateur astronomer Pierre Antonini and Laurent Bernasconi, as well as by American William Koff at the Antelope Hills Observatory in Colorado. The fragmentary lightcurves gave a poorly determined rotation period of 8.65 and 8.90 hours, respectively. Both showed a minuscule brightness amplitude of 0.05 magnitude .
According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Takeishi measures between 5.99 and 6.165 kilometers in diameter and its surface has an albedo between 0.29 and 0.353, while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for a stony asteroid of 0.20, and calculates a diameter of 7.46 kilometers based on an absolute magnitude of 13.0.
This minor planet was named after Japanese amateur astronomer and discoverer of minor planets, Masanori Takeishi (born 1950). Between 1975 and 1993, he was a chief editor of the Japan Astronomical Circular. The official naming citation was published by the Minor Planet Center on 14 December 1997 .