| Discovery[1] | |
|---|---|
| Discovered by | E. Johnson |
| Discovery site | Johannesburg Obs. |
| Discovery date | 25 April 1949 |
| Designations | |
| (1922) Zulu | |
Named after | Zulu(tribe)[2] |
| 1949 HC | |
| main-belt · (outer)[1][3] 2:1 res[4] | |
| Orbital characteristics[1] | |
| Epoch 16 February 2017 (JD 2457800.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 67.70 yr (24,727 days) |
| Aphelion | 4.7945AU |
| Perihelion | 1.6775 AU |
| 3.2360 AU | |
| Eccentricity | 0.4816 |
| 5.82yr (2,126 days) | |
| 187.91° | |
| 0° 10m 9.48s / day | |
| Inclination | 35.446° |
| 226.53° | |
| 31.395° | |
| Earth MOID | 0.7153 AU |
| Jupiter MOID | 0.6296 AU |
| Physical characteristics | |
| Dimensions | 12.41±2.60 km[5] 19.30 km(calculated)[3] 20.561±0.321 km[6][7] |
| 18.64±0.01h[8] 18.65 h[9] | |
| 0.055±0.006[6][7] 0.057(assumed)[3] 0.16±0.05[5] | |
| C[3] | |
| 12.2[6] · 12.27±0.24[10] · 12.3[1][3][5] | |
1922 Zulu, provisional designation1949 HC, is a carbonaceousasteroid in a strongly unstable resonance with Jupiter, located in the outermost regions of theasteroid belt, and approximately 20 kilometers in diameter. It was discovered on 25 April 1949, by South African astronomerErnest Johnson atUnion Observatory in Johannesburg, and named for the South AfricanZulu people.[2][11]
Zulu is one of few strongly unstable asteroids located near the 2:1orbital resonance with the gas giantJupiter, that corresponds to one of the prominentKirkwood gaps in the asteroid belt.[4]
It orbits the Sun at a distance of 1.7–4.8 AU once every 5 years and 10 months (2,126 days). Its orbit has aneccentricity of 0.48 and aninclination of 35° with respect to theecliptic.[1] The body'sobservation arc begins with its official discovery observation at Johannesburg, as noprecoveries were taken and no prior identifications were made.[11]
Zulu was lost shortly after its 1949-discovery(seeLost asteroid), and only rediscovered in 1974 by Richard Eugene McCrosky, Cheng-yuan Shao and JH Bulger based on a predicted position by C. M. Bardwell of theCincinnati Observatory.[12] It is quite highly inclined for asteroids in the asteroid belt, with an inclination of 35.4 degrees. This may be related to its 2:1 resonance with Jupiter.
In May 2002, a rotationallightcurve ofZulu was obtained from photometric observations by American astronomerRobert Stephens at the Santana Observatory in California. Lightcurve analysis gave a well-definedrotation period of 18.64 hours with a brightness variation of 0.11magnitude (U=3).[8] One month later, French amateur astronomersRené Roy and Laurent Brunetto obtained another lightcurve with a concurring period of 18.65 hours and an amplitude of 0.09 magnitude (U=1).[9]
According to the survey carried out by NASA'sWide-field Infrared Survey Explorer with its subsequentNEOWISE mission,Zulu measures 12.41 and 20.561 kilometers in diameter and its surface has analbedo of 0.055 and 0.16.[5][6][7] TheCollaborative Asteroid Lightcurve Link assumes a standard albedo for a carbonaceousC-type asteroid of 0.057 and calculates a diameter of 19.30 kilometers with anabsolute magnitude of 12.3.[3]
Thisminor planet was named after the South AfricanZulu people, in recognition of the tribesmen who devotedly worked at the Johannesburg Union Observatory. The name also closely relates to1362 Griqua and1921 Pala, which also received tribal names and librate in the 2:1 ratio of Jupiter's mean motion as well.[2] The officialnaming citation was published by theMinor Planet Center on 20 February 1976 (M.P.C. 3938).[13]
