| Minorplanet: | yes |
| 9971 Ishihara | |
| Background: |
|
| Discovery Ref: |   |
| Discovered: | 16 April 1993 |
| Mpc Name: | (9971) Ishihara |
| Alt Names: | 1993 HS |
| Named After: | Takahiro Ishihara |
| Mp Category: | main-belt Flora  |
| Orbit Ref: |   |
| Epoch: | 4 September 2017 (JD 2458000.5) |
| Uncertainty: | 0 |
| Observation Arc: | 24.91 yr (9,097 days) |
| Perihelion: | 1.9164 AU |
| Semimajor: | 2.1814 AU |
| Eccentricity: | 0.1215 |
| Period: | 3.22 yr (1,177 days) |
| Mean Motion: | / day |
| Inclination: | 2.7482° |
| Asc Node: | 20.550° |
| Arg Peri: | 246.01° |
| Dimensions: | |
| Rotation: | |
| Pole Ecliptic Lat: | (42.0°, 76.0°) (λ1/β1) |
| Albedo: | |
| Abs Magnitude: | 13.713.9 14.3 |
9971 Ishihara (prov. designation:) is a stony Flora asteroid from the inner regions of the asteroid belt, approximately 5km (03miles) in diameter. It was discovered by Japanese amateur astronomers Kin Endate and Kazuro Watanabe at Kitami Observatory on 16 April 1993, and named after Takahiro Ishihara, president of the astronomical society at Hiroshima.
Ishihara is a member of the Flora family, one of the largest families of stony asteroids in the asteroid belt. It orbits the Sun in the inner main-belt at a distance of 1.9–2.4 AU once every 3 years and 3 months (1,177 days). Its orbit has an eccentricity of 0.12 and an inclination of 3° with respect to the ecliptic. It was first identified as at Karl Schwarzschild Observatory in 1991, extending the body's observation arc by approximately 2 years prior to its official discovery at Kitami.
This minor planet was named after Takahiro Ishihara (born 1961), an observer of comets, communicator of astronomy, and former president of the astronomical society at Hiroshima (1987–1997). The was published by the Minor Planet Center on 6 January 2003 .
In January 2012, a rotational lightcurve of Ishihara was obtained from photometric observations by astronomers at the Palomar Transient Factory in California. Lightcurve analysis gave a rotation period of hours with a brightness amplitude of 1.06 in magnitude, which indicates that the body has a non-spheroidal shape .
A 2016-published lightcurve, using modeled photometric data from the Lowell Photometric Database (LPD), gave a concurring period of 6.71574 hours, as well as a spin axis of (42.0°, 76.0°) in ecliptic coordinates (λ, β).
According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Ishihara measures 4.986 and 5.012 kilometers in diameter and its surface has an albedo of 0.235 and 0.2328, respectively. The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.24 – derived from 8 Flora, a S-type asteroid and the family's largest member and namesake – and calculates a diameter of 3.74 kilometers with an absolute magnitude of 14.3.