801 Helwerthia is a C-type asteroid orbiting in the Main belt near the Eunomia family. However, it is not a family member but an un-related interloper in the region because its composition is inconsistent with membership. Its diameter is about 33 km, its albedo around 0.038.[2] An international team of astronomers observed this minor planet photometrically in 2012, determining a rotation period of 23.93±0.01 h with an amplitude of 0.15±0.03 in magnitude.[3]
| Discovery | |
|---|---|
| Discovered by | Max Wolf |
| Discovery site | Heidelberg Observatory |
| Discovery date | 20 March 1915 |
| Designations | |
MPC designation | (801) Helwerthia |
Alternative designations | 1915 WQ; A924 OD; 1925 RG; 1970 GS1 |
| Orbital characteristics[1] | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 101.08 yr (36918 d) |
| Aphelion | 2.8087 AU (420.18 Gm) |
| Perihelion | 2.4007 AU (359.14 Gm) |
Semi-major axis | 2.6047 AU (389.66 Gm) |
| Eccentricity | 0.078337 |
Orbital period (sidereal) | 4.20 yr (1535.4 d) |
Mean anomaly | 47.6362° |
Mean motion | 0° 14m 4.056s / day |
| Inclination | 14.130° |
Longitude of ascending node | 185.973° |
Argument of perihelion | 335.076° |
| Earth MOID | 1.41172 AU (211.190 Gm) |
| Jupiter MOID | 2.17333 AU (325.126 Gm) |
| TJupiter | 3.366 |
| Physical characteristics | |
Mean radius | 16.615±1.25 km |
Synodic rotation period | 23.93 h (0.997 d) |
Geometric albedo | 0.0384±0.007 |
Absolute magnitude (H) | 11.55 |
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