9175 Graun

9175 Graun
Discovery [1]
Discovered byH. E. Holt
Discovery sitePalomar Obs.
Discovery date29 July 1990
(9175) Graun
Named after
Ken Graun
(American astronomy author)[2]
1990 OO2 · 1975 CL
1980 BB1 · 1986 WS4
1991 XL2
Eunomia[3] · Maria[4]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc42.11 yr (15,382 days)
Aphelion2.9666 AU
Perihelion2.2334 AU
2.6000 AU
4.19 yr (1,531 days)
0° 14m 6.36s / day
Physical characteristics
Dimensions7.929±0.142 km[5][6]
10.23±2.25 km[7]
10.35±0.71 km[8]
10.53 km (calculated)[3]
20 h[4]
25.8±0.5 h[9]
0.21 (assumed)[3]
12.2[1][3] · 12.25±0.38[10] · 12.4[8][5] · 12.66[7]

9175 Graun, provisional designation 1990 OO2, is a stony Eunomian asteroid from the central region of the asteroid belt, approximately 10 kilometers in diameter. It was discovered on 29 July 1990, by American astronomer Henry E. Holt at Palomar Observatory in California, United States.[11] The asteroid was later named for American author and amateur astronomer Ken Graun.[2]

Orbit and classification[]

Graun is a member of the Eunomia family, a large group of S-type asteroids and the most prominent family in the intermediate main-belt. It orbits the Sun at a distance of 2.2–3.0 AU once every 4 years and 2 months (1,531 days). Its orbit has an eccentricity of 0.14 and an inclination of 15° with respect to the ecliptic.[1] In February 1975, it was first identified as 1975 CL at the Karl Schwarzschild Observatory, extending the body's observation arc by 15 years prior to its official discovery observation at Palomar.[11]

Alternative family[]

Based on its concurring orbital elements, Graun has also been group into the Maria family, which is named after its namesake, the asteroid 170 Maria.[4] It is an old-type asteroid family, about (3±1)×109 years old, located near the area of a 3:1 resonances with Jupiter that supplies near-Earth asteroids to the inner Solar System. It is estimated that every 100 million years, about 37 to 75 Maria asteroids larger than 1 kilometer become near-Earth objects.[9]

Physical characteristics[]


In January 2013, a rotational lightcurve of Graun was obtained from photometric observations. Lightcurve analysis gave a rotation period of 25.8 hours with a brightness variation of 0.16 magnitude (U=2+).[9] The measurement supersedes a shorter period of 20 hours with an amplitude of 0.2 magnitude (U=1).[4]

Diameter and albedo[]

According to the surveys carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer and the Japanese Akari satellite, Graun measures 10.23 and 10.35 kilometers in diameter, and its surface has an albedo of 0.20 and 0.183, respectively.[7][8] Preliminary NEOWISE results gave a much higher albedo and consequently shorter diameter.[5][6]

The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.21 – derived from 15 Eunomia, the family's largest member and namesake – and calculates a diameter of 10.53 kilometers with an absolute magnitude of 12.2.[3]


This minor planet was named in honor of American amateur astronomer and publisher Ken Graun (born 1955), author of two books on astronomy, owner of "Ken Press" and the website What's Out tonight?, bringing astronomy to the broader public including children.[2][12] The official naming citation was published by the Minor Planet Center on 9 March 2001 (M.P.C. 42358).[13]


  1. ^ a b c d "JPL Small-Body Database Browser: 9175 Graun (1990 OO2)" (2017-03-21 last obs.). Jet Propulsion Laboratory. Retrieved 22 June 2017.
  2. ^ a b c Schmadel, Lutz D. (2007). "(9175) Graun". Dictionary of Minor Planet Names – (9175) Graun. Springer Berlin Heidelberg. p. 682. doi:10.1007/978-3-540-29925-7_7400. ISBN 978-3-540-00238-3.
  3. ^ a b c d e f "LCDB Data for (9175) Graun". Asteroid Lightcurve Database (LCDB). Retrieved 24 July 2016.
  4. ^ a b c d Alvarez-Candal, Alvaro; Duffard, René; Angeli, Cláudia A.; Lazzaro, Daniela; Fernández, Silvia (December 2004). "Rotational lightcurves of asteroids belonging to families". Icarus. 172 (2): 388–401. Bibcode:2004Icar..172..388A. doi:10.1016/j.icarus.2004.06.008. Retrieved 1 January 2016.
  5. ^ 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". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. Retrieved 24 July 2016.
  6. ^ 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:1109.4096. Bibcode:2011ApJ...741...68M. doi:10.1088/0004-637X/741/2/68. Retrieved 4 December 2016.
  7. ^ a b c d Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; et al. (September 2016). "NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos". The Astronomical Journal. 152 (3): 12. arXiv:1606.08923. Bibcode:2016AJ....152...63N. doi:10.3847/0004-6256/152/3/63. Retrieved 22 June 2017.
  8. ^ 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. (online, AcuA catalog p. 153)
  9. ^ a b c Kim, M.-J.; Choi, Y.-J.; Moon, H.-K.; Byun, Y.-I.; Brosch, N.; Kaplan, M.; et al. (March 2014). "Rotational Properties of the Maria Asteroid Family". The Astronomical Journal. 147 (3): 15. arXiv:1311.5318. Bibcode:2014AJ....147...56K. doi:10.1088/0004-6256/147/3/56.CS1 maint: numeric names: authors list (link)
  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. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 24 July 2016.
  11. ^ a b "9175 Graun (1990 OO2)". Minor Planet Center. Retrieved 24 July 2016.
  12. ^ "What's out tonight?". Ken Press. January 2016. Retrieved 1 January 2016.
  13. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 24 July 2016.

External links[]