989 Schwassmannia
989 Schwassmannia (prov. designation: A922 WD or 1922 MW) is a stony background asteroid and a slow rotator from the central regions of the asteroid belt, approximately 12.5 kilometers (7.8 miles) in diameter. It was discovered on 18 November 1922, by astronomer Friedrich Karl Arnold Schwassmann at the Bergedorf Observatory in Hamburg, Germany. The bright S/T-type asteroid has a long rotation period of 107.9 hours. It was named after the discoverer himself.
| Discovery | |
|---|---|
| Discovered by | A. Schwassmann |
| Discovery site | Bergedorf Obs. |
| Discovery date | 18 November 1922 |
| Designations | |
MPC designation | (989) Schwassmannia |
| Pronunciation | /ʃwæsˈmæniə, ʃvɑːs-/ |
Named after | Friedrich Karl Arnold Schwassmann (discoverer himself) |
Alternative designations | A922 WD · 1922 MW 1935 UE · 1935 UF |
Minor planet category | main-belt · (middle) background |
| Orbital characteristics | |
| Epoch 27 April 2019 (JD 2458600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 96.49 yr (35,244 d) |
| Aphelion | 3.3261 AU |
| Perihelion | 1.9915 AU |
Semi-major axis | 2.6588 AU |
| Eccentricity | 0.2510 |
Orbital period (sidereal) | 4.34 yr (1,584 d) |
Mean anomaly | 83.840° |
Mean motion | 0° 13m 38.28s / day |
| Inclination | 14.700° |
Longitude of ascending node | 243.40° |
| 165.73° | |
| Physical characteristics | |
Mean diameter |
|
Synodic rotation period | 107.85±0.01 h |
| |
| 11.8 | |
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