1922 Zulu

1922 ZuluDiscovery[1]

Discovered by| E. Johnson
Discovery site| Johannesburg Obs.
Discovery date| 25 April 1949
Designations

MPC designation

| (1922) Zulu
Named after| Zulu (tribe)[2]

Alternative designations

| 1949 HC
Minor planet category| 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)
|{{{apsis}}}|helion}}| 4.7945 AU
|{{{apsis}}}|helion}}| 1.6775 AU

Semi-major axis

| 3.2360 AU
Eccentricity| 0.4816
Orbital period| 5.82 yr (2,126 days)
Mean anomaly| 187.91°
Mean motion| 0° 10m 9.48s / day
Inclination| 35.446°
Longitude of ascending node| 226.53°

|{{{apsis}}}|helion}}

| 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]
Rotation period| 18.64±0.01 h[8]
18.65 h[9]
Geometric albedo| 0.055±0.006[6][7]
0.057 (assumed)[3]
0.16±0.05[5]

Spectral type

| C[3]
Absolute magnitude (H)| 12.2[6] * 12.27±0.24[10] * 12.3[1][3][5]

1922 Zulu, provisional designation 1949 HC, is a carbonaceous asteroid in a strongly unstable resonance with Jupiter, located in the outermost regions of the asteroid belt, and approximately 20 kilometers in diameter. It was discovered on 25 April 1949, by South African astronomer Ernest Johnson at Union Observatory in Johannesburg, and named for the South African Zulu people.[2][11]

## Contents

* 1 Orbit and classification
* 2 Physical characteristics
* 3 Naming
* 4 See also
* 5 References
* 6 External links

## Orbit and classification

Zulu is one of few strongly unstable asteroids located near the 2:1 orbital resonance with the gas giant Jupiter, that corresponds to one of the prominent Kirkwood 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 an eccentricity of 0.48 and an inclination of 35° with respect to the ecliptic.[1] The body's observation arc begins with its official discovery observation at Johannesburg, as no precoveries were taken and no prior identifications were made.[11]

Zulu was lost shortly after its 1949-discovery (see Lost 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 the Cincinnati 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.

## Physical characteristics

In May 2002, a rotational lightcurve of Zulu was obtained from photometric observations by American astronomer Robert Stephens at the Santana Observatory in California. Lightcurve analysis gave a well-defined rotation period of 18.64 hours with a brightness variation of 0.11 magnitude ({{{1}}}).[8] One month later, French amateur astronomers René Roy and Laurent Brunetto obtained another lightcurve with a concurring period of 18.65 hours and an amplitude of 0.09 magnitude ({{{1}}}).[9]

According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Zulu measures 12.41 and 20.561 kilometers in diameter and its surface has an albedo of 0.055 and 0.16.[5][6][7] The Collaborative Asteroid Lightcurve Link assumes a standard albedo for a carbonaceous C-type asteroid of 0.057 and calculates a diameter of 19.30 kilometers with an absolute magnitude of 12.3.[3]

## Naming

This minor planet was named after the South African Zulu people, in recognition of the tribesmen who devotedly worked at the Johannesburg Union Observatory. The name also closely relates to 1362 Griqua and 1921 Pala, which also received tribal names and librate in the 2:1 ratio of Jupiter's mean motion as well.[2] The official naming citation was published by the Minor Planet Center on 20 February 1976 (M.P.C. 3938).[13]

## See also

* Griqua group

## References

1. ↑ 1.0 1.1 1.2 1.3 1.4 "JPL Small-Body Database Browser: 1922 Zulu (1949 HC)". Jet Propulsion Laboratory. https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2001922.
2. ↑ 2.0 2.1 2.2 Schmadel, Lutz D. (2007). "(1922) Zulu". Dictionary of Minor Planet Names – (1922) Zulu. Springer Berlin Heidelberg. p. 154. doi:10.1007/978-3-540-29925-7_1923. ISBN 978-3-540-00238-3.
3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 "LCDB Data for (1922) Zulu". Asteroid Lightcurve Database (LCDB). http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=1922|Zulu.
4. ↑ 4.0 4.1 Roig, F.; Nesvorný, D.; Ferraz-Mello, S. (September 2002). "Asteroids in the 2 : 1 resonance with Jupiter: dynamics and size distribution [ Erratum: 2002MNRAS.336.1391R "]. Monthly Notices of the Royal Astronomical Society 335 (2): 417–431. doi:10.1046/j.1365-8711.2002.05635.x. Bibcode: 2002MNRAS.335..417R. http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2002MNRAS.335..417R. Retrieved 31 March 2017.
5. ↑ 5.0 5.1 5.2 5.3 Nugent, C. R.; Mainzer, A.; Masiero, J.; Bauer, J.; Cutri, R. M.; Grav, T. et al. (December 2015). "NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos". The Astrophysical Journal 814 (2): 13. doi:10.1088/0004-637X/814/2/117. Bibcode: 2015ApJ...814..117N. http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2015ApJ...814..117N. Retrieved 31 March 2017.
6. ↑ 6.0 6.1 6.2 6.3 Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D. et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal 741 (2): 25. doi:10.1088/0004-637X/741/2/90. Bibcode: 2011ApJ...741...90M.
7. ↑ 7.0 7.1 7.2 Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Dailey, J. et al. (November 2011). "Main Belt Asteroids with WISE/NEOWISE. I. Preliminary Albedos and Diameters". The Astrophysical Journal 741 (2): 20. doi:10.1088/0004-637X/741/2/68. Bibcode: 2011ApJ...741...68M. http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2011ApJ...741...68M. Retrieved 31 March 2017.
8. ↑ 8.0 8.1 Stephens, R. D. (December 2002). "Photometry of 769 Tatjana, 818 Kapteyna, 1922 Zulu, and 3687 Dzus". The Minor Planet Bulletin 29: 72. Bibcode: 2002MPBu...29...72S. http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2002MPBu...29...72S. Retrieved 31 March 2017.
9. ↑ 9.0 9.1 Behrend, Raoul. "Asteroids and comets rotation curves – (1922) Zulu". Geneva Observatory. http://obswww.unige.ch/~behrend/page4cou.html#001922.
10. ↑ Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus 261: 34–47. doi:10.1016/j.icarus.2015.08.007. Bibcode: 2015Icar..261...34V. http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2015Icar..261...34V. Retrieved 31 March 2017.
11. ↑ 11.0 11.1 "1922 Zulu (1949 HC)". Minor Planet Center. https://www.minorplanetcenter.net/db_search/show_object?object_id=1922.
12. ↑ Brian G. Marsden (24 October 1974). "International Astronomical Union Circular 2710 – 1949 HC (3rd item)". Central Bureau for Astronomical Telegrams. http://www.cbat.eps.harvard.edu/iauc/02700/02710.html#Item3.
13. ↑ Schmadel, Lutz D. (2009). "Appendix – Publication Dates of the MPCs". Dictionary of Minor Planet Names – Addendum to Fifth Edition (2006–2008). Springer Berlin Heidelberg. p. 221. doi:10.1007/978-3-642-01965-4. ISBN 978-3-642-01964-7. https://archive.org/details/dictionaryminorp2008schm.

## External links

* Asteroid Lightcurve Database (LCDB), query form (info )
* Dictionary of Minor Planet Names, Google books
* Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
* Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
* 1922 Zulu at AstDyS-2, Asteroids—Dynamic Site
* Ephemeris * Observation prediction * Orbital info * Proper elements * Observational info
* 1922 Zulu at the JPL Small-Body Database
* Close approach * Discovery * Ephemeris * Orbit diagram * Orbital elements * Physical parameters

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