1691 Oort
| Lightcurve-based 3D-model of Oort | |
| Discovery | |
|---|---|
| Discovered by | K. Reinmuth I. Groeneveld | 
| Discovery site | Heidelberg Obs. | 
| Discovery date | 9 September 1956 | 
| Designations | |
| (1691) Oort | |
| Named after | Jan Oort (astronomer) | 
| 1956 RB · 1945 TD 1947 DA · 1950 PZ 1950 RU · 1951 XW 1955 MW · 1956 SD 1964 DA · A917 TD | |
| main-belt · Themis | |
| Orbital characteristics | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 71.42 yr (26,086 days) | 
| Aphelion | 3.7153 AU | 
| Perihelion | 2.6084 AU | 
| 3.1618 AU | |
| Eccentricity | 0.1750 | 
| 5.62 yr (2,054 days) | |
| 240.25° | |
| Inclination | 1.0860° | 
| 174.55° | |
| 232.69° | |
| Physical characteristics | |
| Dimensions | 27.13 km (calculated) 33.163±0.534 km 33.644±0.267 37.37±0.74 km | 
| 10.2684±0.0005 h 10.2705±0.0004 h | |
| 0.053±0.002 0.065±0.011 0.0672±0.0150 0.10 (assumed) | |
| Tholen = CU · CU B–V = 0.682 U–B = 0.316 | |
| 10.90±0.12 · 10.95 | |
1691 Oort, provisional designation 1956 RB, is a rare-type carbonaceous Themistian asteroid from the outer region of the asteroid belt, approximately 33 kilometers in diameter.
It was discovered on 9 September 1956, by German astronomer Karl Reinmuth and Dutch astronomer Ingrid van Houten-Groeneveld at Heidelberg Observatory in south-west Germany. It was later named after Dutch astronomer Jan Oort.