_Ishihara.png) Shape model ofIshihara from itslightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | K. Endate K. Watanabe |
| Discovery site | Kitami Observatory |
| Discovery date | 16 April 1993 |
| Designations | |
| (9971) Ishihara | |
Named after | Takahiro Ishihara (Japanese astronomer)[2] |
| 1993 HS · 1991 YC2 1996 EU1 | |
| main-belt[1][3] · Flora[4] | |
| Orbital characteristics[3] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 24.91 yr (9,097 days) |
| Aphelion | 2.4465AU |
| Perihelion | 1.9164 AU |
| 2.1814 AU | |
| Eccentricity | 0.1215 |
| 3.22yr (1,177 days) | |
| 158.69° | |
| 0° 18m 21.24s / day | |
| Inclination | 2.7482° |
| 20.550° | |
| 246.01° | |
| Physical characteristics | |
| Dimensions | 4.986±0.053 km[5] 5.012±0.069 km[6] |
| 6.715±0.0036 h[7] 6.71574±0.00001 h[8] | |
| (42.0°, 76.0°) (λ1/β1)[8] | |
| 0.2328±0.0281[6] 0.235±0.027[5] | |
| S(assumed)[4] | |
| 13.7[6] · 13.9[3] · 13.852±0.006(R)[7] · 14.3[4] | |
9971 Ishihara (prov. designation:1993 HS) is a stonyFlora asteroid from the inner regions of theasteroid belt, approximately 5 kilometers (3.1 miles) in diameter. It was discovered by Japanese amateur astronomersKin Endate andKazuro Watanabe atKitami Observatory on 16 April 1993,[1] and named afterTakahiro Ishihara, president of the astronomical society at Hiroshima.[2]
Ishihara is a member of theFlora family, one of the largest families ofstony asteroids in the asteroid belt. It orbits the Sun in theinner main-belt at a distance of 1.9–2.4 AU once every 3 years and 3 months (1,177 days). Its orbit has aneccentricity of 0.12 and aninclination of 3° with respect to theecliptic.[3] It was first identified as1991 YC2 atKarl Schwarzschild Observatory in 1991, extending the body'sobservation arc by approximately 2 years prior to its official discovery at Kitami.[1]
Thisminor planet was named after Takahiro Ishihara (born 1961), an observer ofcomets, communicator of astronomy, and former president of the astronomical society at Hiroshima (1987–1997).[2] Theofficial naming citation was published by theMinor Planet Center on 6 January 2003 (M.P.C. 47298).[9]
In January 2012, a rotationallightcurve ofIshihara was obtained fromphotometric observations by astronomers at thePalomar Transient Factory in California. Lightcurve analysis gave arotation period of6.715±0.0036 hours with a brightness amplitude of 1.06 inmagnitude, which indicates that the body has a non-spheroidal shape (U=2).[7]
A 2016-published lightcurve, using modeled photometric data from the Lowell Photometric Database (LPD), gave a concurring period of 6.71574 hours (U=n.a.), as well as aspin axis of (42.0°, 76.0°) inecliptic coordinates (λ, β).[8]
According to the survey carried out by NASA'sWide-field Infrared Survey Explorer with its subsequentNEOWISE mission,Ishihara measures 4.986 and 5.012 kilometers in diameter and its surface has analbedo of 0.235 and 0.2328, respectively.[5][6] TheCollaborative Asteroid Lightcurve Link assumes an albedo of 0.24 – derived from8 Flora, aS-type asteroid and the family's largest member and namesake – and calculates a diameter of 3.74 kilometers with anabsolute magnitude of 14.3.[4]
