1881 Shao

1881 Shao, provisional designation 1940 PC or 1968 OO, is a background asteroid from the outer regions of the asteroid belt, approximately 25 kilometers (16 miles) in diameter. It was discovered on 3 August 1940, by German astronomer Karl Reinmuth at the Heidelberg Observatory in southwest Germany.[1] The presumed C-type asteroid has a rotation period of 7.45 hours.[7] It was named for Chinese astronomer Cheng-yuan Shao.[1]

1881 Shao
Discovery [1]
Discovered byK. Reinmuth
Discovery siteHeidelberg Obs.
Discovery date3 August 1940
(1881) Shao
Named after
Cheng-yuan Shao[1]
(Chinese astronomer)
1940 PC · 1968 OO
main-belt[1][2] · (outer)
Orbital characteristics[2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc77.71 yr (28,385 d)
Aphelion3.5061 AU
Perihelion2.8339 AU
3.1700 AU
5.64 yr (2,062 d)
0° 10m 28.56s / day
Physical characteristics
Mean diameter
24.083±0.134 km[4]
25.437±0.176 km[5]
25.46±0.86 km[6]
29.21 km (calculated)[7]
5.61±0.07 h[8]
7.452±0.002 h[9]
0.057 (assumed)[7]
C (assumed)[7]
11.19±0.04 (R)[8]

Orbit and classificationEdit

Shao is a non-family asteroid from the main belt's background population.[3] It orbits the Sun in the outer main-belt at a distance of 2.8–3.5 AU once every 5 years and 8 months (2,062 days; semi-major axis of 3.17 AU). Its orbit has an eccentricity of 0.11 and an inclination of 10° with respect to the ecliptic.[2] The body's observation arc begins with its official discovery observation at Heidelberg in 1940.[1]

Physical characteristicsEdit

Shao is an assumed carbonaceous C-type asteroid.[7]

Rotation periodEdit

In July 2013, a rotational lightcurve of Shao was obtained from photometric observations by Italian amateur astronomer Silvano Casulli. Lightcurve analysis gave a rotation period of 7.452 hours with a brightness variation of 0.15 magnitude (U=2).[9] A second lightcurve by astronomers at the Palomar Transient Factory from December 2014, gave a shorter period of 5.61 hours and an amplitude of 0.11 (U=2), indicative for a rather spherical shape.[7][8]

Diameter and albedoEdit

According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Shao measures between 24.083 and 25.46 kilometers in diameter and its surface has an albedo between 0.0994 and 0.115.[4][5][6] The Collaborative Asteroid Lightcurve Link assumes a standard albedo for a carbonaceous asteroid of 0.057, and calculates a diameter of 29.21 kilometers based on an absolute magnitude of 11.4.[7]


This minor planet was named after Chinese astronomer Cheng-yuan Shao (born 1927), an assistant to Richard McCrosky (see previously numbered 1880 McCrosky) in Harvard's minor-planet program at the Harvard–Smithsonian Center for Astrophysics and Oak Ridge Observatory in Massachusetts, United States. Shao was also involved in the recovery of near-Earth asteroid 1862 Apollo.[1] The official naming citation was published by the Minor Planet Center on 20 February 1976 (M.P.C. 3936).[11]


  1. ^ a b c d e f g "1881 Shao (1940 PC)". Minor Planet Center. Retrieved 9 May 2018.
  2. ^ a b c d "JPL Small-Body Database Browser: 1881 Shao (1940 PC)" (2018-04-21 last obs.). Jet Propulsion Laboratory. Retrieved 9 May 2018.
  3. ^ a b "Asteroid 1881 Shao". Small Bodies Data Ferret. Retrieved 20 October 2019.
  4. ^ 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.
  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. (catalog)
  6. ^ 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 17 October 2019. (online, AcuA catalog p. 153)
  7. ^ a b c d e f g h "LCDB Data for (1881) Shao". Asteroid Lightcurve Database (LCDB). Retrieved 9 May 2018.
  8. ^ a b c Chang, Chan-Kao; Lin, Hsing-Wen; Ip, Wing-Huen; Prince, Thomas A.; Kulkarni, Shrinivas R.; Levitan, David; et al. (December 2016). "Large Super-fast Rotator Hunting Using the Intermediate Palomar Transient Factory". The Astrophysical Journal Supplement Series. 227 (2): 13. arXiv:1608.07910. Bibcode:2016ApJS..227...20C. doi:10.3847/0067-0049/227/2/20.
  9. ^ a b Behrend, Raoul. "Asteroids and comets rotation curves – (1881) Shao". Geneva Observatory. Retrieved 9 May 2018.
  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.
  11. ^ 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.

External linksEdit