2017 OF201
2017 OF201 imaged by the Canada–France–Hawaii Telescope on 31 August 2011 | |
| Discovery | |
|---|---|
| Discovered by | Sihao Cheng, Jiaxuan Li, Eritas Yang |
| Discovery site | Cerro Tololo Inter-American Observatory |
| Discovery date | 23 July 2017 (date of first observation) |
| Designations | |
| 2017 OF201 | |
| TNO, SDO and eTNO | |
| Orbital characteristics (barycentric) | |
| Epoch 5 May 2025 (JD 2460800.5) | |
| Uncertainty parameter 3 | |
| Observation arc | 14.11 yr (5,153 days) (using 25 observations) |
| Earliest precovery date | 21 Sep 2004 |
| Aphelion | 1632±14 AU 1700±60 AU (heliocentric) |
| Perihelion | 44.9 AU |
| 840 AU | |
| Eccentricity | 0.946 |
| 24200 years 24300 years 26000±1300 yr (heliocentric) | |
| 1.3° | |
| 0° 38m 7.8s / day | |
| Inclination | 16.2° |
| 329° | |
| November 1930 ± 1 month | |
| 338° | |
| Physical characteristics | |
| ≈ 550 to 850 km (calc. for a typical TNO albedo of 0.15) | |
| B–V = 0.99±0.11 g–r = 0.77±0.11 r–z = 0.80±0.07 | |
| 22.8 | |
| 3.52±0.45 | |
2017 OF201 is an extreme trans-Neptunian object and dwarf planet candidate, estimated to be at least 550 kilometres (340 miles) in diameter. It was announced in 2025 by Sihao Cheng, Jiaxuan Li, and Eritas Yang, who discovered the object in archived telescope images from 2011 to 2018. With an absolute magnitude of between 3 and 4, 2017 OF201 may be the brightest known object in the Solar System that does not have a directly estimated size. The orbit of 2017 OF201 is extremely large and elongated, bringing it from 45 to 1,630 astronomical units (0.00071 to 0.02577 ly) away from the Sun.