991 McDonalda
Main-belt asteroid
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991 McDonalda is a Themistian asteroid. It was discovered by Otto Struve in 1922 at the Yerkes Observatory in Williams Bay, Wisconsin, United States. It is named after the McDonald Observatory, which Struve helped found in 1939.[2]
Discoverydate24 October 1922
Named after
McDonald Observatory| Discovery | |
|---|---|
| Discovered by | O. Struve |
| Discovery site | Williams Bay |
| Discovery date | 24 October 1922 |
| Designations | |
Named after | McDonald Observatory |
| 1922 NB, 1949 PF, 1950 WG, 1953 GT1, 1975 EE6 | |
| Orbital characteristics[1] | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 80.10 yr (29255 days) |
| Aphelion | 3.6381 AU (544.25 Gm) |
| Perihelion | 2.6458 AU (395.81 Gm) |
| 3.1419 AU (470.02 Gm) | |
| Eccentricity | 0.15791 |
| 5.57 yr (2034.2 d) | |
| 351.48° | |
| 0° 10m 37.092s / day | |
| Inclination | 2.0696° |
| 63.255° | |
| 254.682° | |
| Physical characteristics | |
| 15.705±1.05 km | |
| 0.0638±0.009 | |
| C | |
| 11.12 | |
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