1362 Griqua

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1362 Griqua
Discovery [1]
Discovered by C. Jackson
Discovery site Johannesburg Obs.
Discovery date 31 July 1935
MPC designation (1362) Griqua
Named after
Griqua people[2]
(South African tribe)
1935 QG1 · 1931 BN
main-belt · (outer)[3][4]
Griqua[5] · background[6]
ACO [7]
Orbital characteristics[3]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc 87.03 yr (31,788 d)
Aphelion 4.4123 AU
Perihelion 2.0213 AU
3.2168 AU
Eccentricity 0.3716
5.77 yr (2,107 d)
0° 10m 14.88s / day
Inclination 24.223°
TJupiter 2.9490
Physical characteristics
Mean diameter
25.60±3.72 km[8]
26.936±0.363 km[9][10]
28.36±0.40 km[11]
29.90±1.5 km[12]
29.9±3.0 km[13]
30±3 km[14]
31.0 km (radiometric)[6]
6.891±0.0297 h[15]
6.9±0.1 h[16]
6.907±0.003 h[17]
7 h (poor)[18]
0.055 (radiometric)[6]
Tholen = CP[3][4]
B (S3OS2)[7][19]
U–B = 0.360[3]
B–V = 0.720[3]
11.561±0.003 (S)[15]

1362 Griqua, provisional designation 1935 QG1 is a dark, Jupiter-resonant background asteroid on an eccentric, cometary-like orbit and the namesake of the Griqua group, located in the Hecuba gap in the outermost region of the asteroid belt.[5] The carbonaceous asteroid measures approximately 28 kilometers (17 miles) in diameter and has a rotation period of 6.9 hours.[4] It was discovered on 31 July 1935, by South-African astronomer Cyril Jackson at Union Observatory in Johannesburg,[1] the asteroid was named after the Griqua people in South Africa and Namibia.[2]

Orbit and classification[edit]

Griqua is an asteroid in a cometary orbit (ACO), with no observable coma but with a Tisserand's parameter of 2.95,[3] below the threshold of 3.0 defined for main-belt asteroids. ACO's may be extinct comets,[7] it is the namesake and largest member of the small dynamical Griqua group (known as the "Griquas"), a marginally unstable group of asteroids observed in the Hecuba gap, a resonant zone with the gas giant Jupiter (2/1J).[5] Griqua itself is background asteroids and does not belong to any known asteroid family.[6]

This asteroid orbits the Sun in the outermost asteroid belt at a distance of 2.0–4.4 AU once every 5 years and 9 months (2,107 days; semi-major axis of 3.22 AU). Its orbit has a high eccentricity of 0.37 and an inclination of 24° with respect to the ecliptic.[3]

The body's observation arc begins with its first observation as 1931 BN at Lowell Observatory in January 1931, more than 4 years prior to its official discovery observation at Johannesburg.[1]

Groups in the Hecuba gap[edit]

The marginally unstable Griqua group includes 3688 Navajo, 4177 Kohman and 11665 Dirichlet, while the stable 2:1 resonant group are the "Zhongguos", named after 3789 Zhongguo. The transition between these two groups, however, is not clear, the unnamed, third group in the Hecuba gap are strongly unstable. Their largest members are the asteroids 1921 Pala, 1922 Zulu and 5201 Ferraz-Mello, as well as 5370 Taranis, 8373 Stephengould, and 9767 Midsomer Norton.[5]:422,423

Physical characteristics[edit]

In the Tholen classification, Griqua's spectral type is ambiguous, closest to a common C-type asteroid and somewhat similar to an primitive P-type asteroid (CP).[3][4] The asteroid has also been characterized as a "brighter" B-type asteroid in both the Tholen- and SMASS-like taxonomy of the Small Solar System Objects Spectroscopic Survey (S3OS2).[7][19]

Rotation period[edit]

In November 2000, a rotational lightcurve of Griqua was obtained from photometric observations by Colin Bembrick at the Mount Tarana Observatory in Australia. Lightcurve analysis gave a well-defined rotation period of 6.907 hours with a brightness variation of 0.25 magnitude (U=3).[17] In 2009, follow-up observations by Jean and Milan Strajnic (511), Alain Klotz and Raoul Behrend as well as observations in the S-band by astronomers at the Palomar Transient Factory in California gave a concurring period of 6.891 and 6.9 hours with an amplitude of 0.23 and 0.24 magnitude, respectively (U=2/2).[15][16] The result supersedes a measurement of 7 hours made in the 1970s (U=1).[18]

Diameter and albedo[edit]

According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Griqua measures between 25.60 and 30 kilometers in diameter and its surface has an albedo between 0.0667 and 0.091.[8][9][10][11][12][13][14]

The Collaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an albedo of 0.0667 with a diameter of 29.90 kilometers based on an absolute magnitude of 11.18,[4] while fragmentary radiometric observations in the 1970s determined a diameter of 31.0 kilometer and a derived albedo of 0.055 (TRIAD).[6][a]


This minor planet is named after the Afrikaans-speaking Griqua people, a mixed tribe of Bushman and Khoikhoi descent in Griqualand in South Africa and Namibia. The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 24).[2]


  1. ^ The TRIAD radiometric diameters and albedos (Tucson Revised Index of Asteroid Data). The radiometric observations used for the Tucson Revised Index of Asteroid Data (TRIAD) compilation consist of broadband radiometry at 10 microns (the N band) and 20 microns (the Q band). Observations from 1972 through 1978 have been used, the results are compiled in Morrison and Zellner (1979). References to the observation papers for each entry are given in the associated references file, the observations have been interpreted with the standard model described in Morrison and Lebofsky (1979), using the computer code of Jones and Morrison (1974). Further details of the analysis are described in Morrison and Lebofsky (1979).


  1. ^ a b c "1362 Griqua (1935 QG1)". Minor Planet Center. Retrieved 16 May 2018. 
  2. ^ a b c Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (1362) Griqua. Springer Berlin Heidelberg. p. 110. ISBN 978-3-540-00238-3. Retrieved 31 March 2017. 
  3. ^ a b c d e f g h i "JPL Small-Body Database Browser: 1362 Griqua (1935 QG1)" (2018-01-27 last obs.). Jet Propulsion Laboratory. Retrieved 16 May 2018. 
  4. ^ a b c d e f "LCDB Data for (1362) Griqua". Asteroid Lightcurve Database (LCDB). Retrieved 16 May 2018. 
  5. ^ a b c d Roig, F.; Nesvorný, D.; Ferraz-Mello, S. (September 2002). "Asteroids in the 2 : 1 resonance with Jupiter: dynamics and size distribution" (PDF). Monthly Notices of the Royal Astronomical Society. 335 (2): 417–431. Bibcode:2002MNRAS.335..417R. doi:10.1046/j.1365-8711.2002.05635.x. Retrieved 16 May 2018. 
  6. ^ a b c d e "Asteroid 1362 Griqua". Small Bodies Data Ferret. Retrieved 16 May 2018. 
  7. ^ a b c d Licandro, J.; Alvarez-Candal, A.; de León, J.; Pinilla-Alonso, N.; Lazzaro, D.; Campins, H. (April 2008). "Spectral properties of asteroids in cometary orbits" (PDF). Astronomy and Astrophysics. 481 (3): 861–877. Bibcode:2008A&A...481..861L. doi:10.1051/0004-6361:20078340. Retrieved 16 May 2018. 
  8. ^ a b c d Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Nugent, C.; et al. (November 2012). "Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids" (PDF). The Astrophysical Journal Letters. 759 (1): 5. arXiv:1209.5794Freely accessible. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8. Retrieved 16 May 2018. 
  9. ^ a b c 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. arXiv:1109.4096Freely accessible. Bibcode:2011ApJ...741...68M. doi:10.1088/0004-637X/741/2/68. Retrieved 16 May 2018. 
  10. ^ a b c d Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results" (PDF). The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407Freely accessible. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. Retrieved 16 May 2018.  (catalog)
  11. ^ a b c d Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. Retrieved 16 May 2018.  Online catalog
  12. ^ a b c d Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System. Bibcode:2004PDSS...12.....T. Retrieved 16 May 2018. 
  13. ^ a b c d Alí-Lagoa, V.; Licandro, J.; Gil-Hutton, R.; Cañ; ada-Assandri, M.; Delbo', M.; et al. (June 2016). "Differences between the Pallas collisional family and similarly sized B-type asteroids". Astronomy and Astrophysics. 591: 11. Bibcode:2016A&A...591A..14A. doi:10.1051/0004-6361/201527660. Retrieved 16 May 2018. 
  14. ^ a b c d Alí-Lagoa, V.; de León, J.; Licandro, J.; Delbó, M.; Campins, H.; Pinilla-Alonso, N.; et al. (June 2013). "Physical properties of B-type asteroids from WISE data". Astronomy and Astrophysics. 554: 16. arXiv:1303.5487Freely accessible. Bibcode:2013A&A...554A..71A. doi:10.1051/0004-6361/201220680. Retrieved 16 May 2018. 
  15. ^ a b c Waszczak, Adam; Chang, Chan-Kao; Ofek, Eran O.; Laher, Russ; Masci, Frank; Levitan, David; et al. (September 2015). "Asteroid Light Curves from the Palomar Transient Factory Survey: Rotation Periods and Phase Functions from Sparse Photometry" (PDF). The Astronomical Journal. 150 (3): 35. arXiv:1504.04041Freely accessible. Bibcode:2015AJ....150...75W. doi:10.1088/0004-6256/150/3/75. Retrieved 16 May 2018. 
  16. ^ a b Behrend, Raoul. "Asteroids and comets rotation curves – (1362) Griqua". Geneva Observatory. Retrieved 16 May 2018. 
  17. ^ a b Bembrick, C. (September 2001). "Lightcurves and Period Determination for 1362 Griqua". The Minor Planet Bulletin. 28: 42–43. Bibcode:2001MPBu...28...42B. Retrieved 16 May 2018. 
  18. ^ a b Taylor, R. C.; Gehrels, T.; Capen, R. C. (September 1976). "Minor planets and related objects. XXI - Photometry of eight asteroids". Astronomical Journal: 778–786.NASA–supportedresearch. Bibcode:1976AJ.....81..778T. doi:10.1086/111953. Retrieved 16 May 2018. 
  19. ^ a b Lazzaro, D.; Angeli, C. A.; Carvano, J. M.; Mothé-Diniz, T.; Duffard, R.; Florczak, M. (November 2004). "S3OS2: the visible spectroscopic survey of 820 asteroids" (PDF). Icarus. 172 (1): 179–220. Bibcode:2004Icar..172..179L. doi:10.1016/j.icarus.2004.06.006. Retrieved 16 May 2018. 
  20. ^ 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" (PDF). Icarus. 261: 34–47. arXiv:1506.00762Freely accessible. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 16 May 2018. 

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