| Discovery [1] | |
|---|---|
| Discovered by | K. Endate K. Watanabe |
| Discovery site | Kitami Obs. |
| Discovery date | 23 March 1992 |
| Designations | |
| (5692) Shirao | |
Named after | Motomaro Shirao (geologist,photographer)[2] |
| 1992 FR · 1949 KK 1966 FO · 1966 FS 1970 CH · 1976 SN2 1979 HT2 · 1979 HV1 1985 UW2 · 1989 SO9 | |
| main-belt · Eunomia [3] | |
| Orbital characteristics [1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 67.83 yr (24,776 days) |
| Aphelion | 3.1373AU |
| Perihelion | 2.1723 AU |
| 2.6548 AU | |
| Eccentricity | 0.1818 |
| 4.33yr (1,580 days) | |
| 287.13° | |
| 0° 13m 40.44s / day | |
| Inclination | 11.931° |
| 181.78° | |
| 44.251° | |
| Physical characteristics | |
| Dimensions | 9.17 km(calculated)[3] 9.548±0.155[4] 9.75±0.30 km[5] 9.811±0.063 km[6] |
| 2.886±0.002h[7] 2.8878±0.0004 h[a] 2.90±0.02 h(ii)[8] | |
| 0.21(assumed)[3] 0.2218±0.0290[6] 0.223±0.030[4][5] | |
| S [3][9] | |
| 12.3[5][6] · 12.47±0.25[9] · 12.5[1][3] | |
5692 Shirao, provisional designation1992 FR, is a stony Eunomiaasteroid from the middle region of theasteroid belt, approximately 9 kilometers in diameter. It was discovered on 23 March 1992, by Japanese amateur astronomersKin Endate andKazuro Watanabe atKitami Observatory, Hokkaidō, Japan.[10] The asteroid was later named for Japanese geologist andastrophotographerMotomaro Shirao.[2]
Shirao is a member of theEunomia family, a large group ofstony asteroids and the most prominent family in the intermediate main-belt. It orbits the Sun in thecentral main-belt at a distance of 2.2–3.1 AU once every 4 years and 4 months (1,580 days). Its orbit has aneccentricity of 0.18 and aninclination of 12° with respect to theecliptic.[1]
In 1949, it was first identified as1949 KK atGoethe Link Observatory. The body'sobservation arc begins in 1955, with aprecovery atPalomar Observatory, 37 years prior to its official discovery observation at Kitami.[10]
In June 2014, a rotationallightcurve ofShirao was obtained from photometric observations made by American astronomerBrian Warner at his Palmer Divide Observatory (716) in Colorado. It gave a well-definedrotation period of2.8878 hours with a brightness variation of 0.16magnitude (U=3).[a]
Previous lightcurves were obtained by French astronomerRené Roy (2.90 hours, Δ 0.13 mag,U=2) in June 2001,[8] by American astronomerDonald P. Pray (2.886 hours, Δ 0.12 mag,U=2) in March 2005,[7] and by astronomers Dominique Suys, Hugo Riemis and Jan Vantomme (2.90 hours, Δ 0.15 mag,U=2+) in September 2006.[3][8]
According to the surveys carried out by NASA'sWide-field Infrared Survey Explorer and its subsequentNEOWISE mission,Shirao measures between 9.5 and 9.8 kilometers in diameter and its surface has analbedo of 0.22,[4][5][6] while theCollaborative Asteroid Lightcurve Link assumes a standard albedo of 0.21 – derived from15 Eunomia, the largest member and namesake of this asteroid family – and calculates a diameter of 9.2 kilometers.[3]
Thisminor planet was named after Motomaro Shirao (born 1953), a Japanesegeologist andastrophotographer, who is known for his photographs of volcanoes and lunargeological features.[2] The official naming citation was published by theMinor Planet Center on 4 April 1996 (M.P.C. 26930).[11]
