| Discovery[1] | |
|---|---|
| Discovered by | T. Gehrels |
| Discovery site | Palomar Obs. |
| Discovery date | 20 September 1973 |
| Designations | |
| (1921) Pala | |
Named after | Pala(Indian reservation)[2] |
| 1973 SE | |
| main-belt · (outer)[1] background[3] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 43.52 yr (15,895 days) |
| Aphelion | 4.5807AU |
| Perihelion | 2.0148 AU |
| 3.2978 AU | |
| Eccentricity | 0.3890 |
| 5.99yr (2,187 days) | |
| 165.04° | |
| 0° 9m 52.56s / day | |
| Inclination | 19.192° |
| 352.31° | |
| 20.092° | |
| Physical characteristics | |
| Dimensions | 8.2 km[4]: 422 |
| 14.3[5] · 14.6[1] | |
1921 Pala, provisional designation1973 SE is a backgroundasteroid in an unstable orbit located in the outer region ofasteroid belt, approximately 8.2 kilometers in diameter. It is one of very few bodies located in the 2 : 1mean motion resonance withJupiter.[4] It was discovered by Dutch–American astronomerTom Gehrels atPalomar Observatory on 20 September 1973.[6]
Pala is a non-family background asteroid from the main belt'sbackground population.[3] It orbits the Sun in theouter asteroid belt at a distance of 2.0–4.6 AU once every 5 years and 12 months (2,187 days;semi-major axis of 3.30 AU). Its orbit has aneccentricity of 0.39 and aninclination of 19° with respect to theecliptic.[1] The body'sobservation arc begins at Palomar with its official discovery observation.[6]
It has a strongly unstable orbit near the 2:1orbital resonance withJupiter. The asteroid's orbit is expected to persist for another 18 million years though.[4]
Pala measures approximately 8.2 kilometers in diameter, while thealbedo of its surface has not been estimated.[4] As of 2017, the body'sspectral type as well as itsrotation period and shape remain unknown.[1][7]
Thisminor planet is named after theIndian reservation,Pala, located at the base ofPalomar Mountain, believed to apply to an Indian tribe whose members have lived in the area for many centuries.[2] The officialnaming citation was published by theMinor Planet Center on 20 February 1976 (M.P.C. 3938).[8]
