1831 Nicholson, provisional designation 1968 HC, is a stony asteroid of the Baptistina family from the inner regions of the asteroid belt, approximately 8 kilometers (5 miles) in diameter. It was discovered on 17 April 1968, by Swiss astronomer Paul Wild at the Zimmerwald Observatory near Bern, Switzerland.[1] The S-type asteroid has a rotation period of 3.2 hours. It was named for American astronomer Seth B. Nicholson.[2]

1831 Nicholson
Discovery [1]
Discovered byP. Wild
Discovery siteZimmerwald Obs.
Discovery date17 April 1968
MPC designation(1831) Nicholson
Named after
Seth B. Nicholson[2]
(American astronomer)
1968 HC · 1948 GF
1955 ML
main-belt[1][3] · (inner)
Baptistina[4] · Flora[4][5]
Orbital characteristics[3]
Epoch 27 April 2019 (JD 2458600.5)
Uncertainty parameter 0
Observation arc62.92 yr (22,982 d)
Aphelion2.5257 AU
Perihelion1.9527 AU
2.2392 AU
3.35 yr (1,224 d)
0° 17m 38.76s / day
Physical characteristics
Mean diameter
7.10±1.29 km[6]
8.08±0.47 km[7][8]
3.228±0.001 h[9]
SMASS = S[3][5]

Orbit and classificationEdit

According to a HCM-analysis by David Nesvorný, Nicholson is a member of the Baptistina family (403),[4] located within the greater Flora family a giant asteroid clan and the largest family of stony asteroids in the asteroid belt.[5][4][10] Conversely, and since the existence of a proper Flora family has been ruled out by other astronomers, Nicholson has also been classified as a background asteroid.[11]

It orbits the Sun in the inner main-belt at a distance of 2.0–2.5 AU once every 3 years and 4 months (1,224 days; semi-major axis of 2.24 AU). Its orbit has an eccentricity of 0.13 and an inclination of 6° with respect to the ecliptic.[3] The asteroid was first observed as 1948 GF at the Nice Observatory in April 1948. The body's observation arc begins with its observation as 1955 ML at the Goethe Link Observatory in June 1955, almost 13 years prior to its official discovery observation at Zimmerwald.[1]


This minor planet was named by the discoverer in memory of American astronomer Seth B. Nicholson (1891–1963), who pioneered in several branches of planetary research at Mount Wilson Observatory and who discovered four of Jupiter's numerous moons – namely, Sinope, Lysithea, Carme, and Ananke. The lunar crater Nicholson and the dark terrain of Nicholson Regio on Jupiter's moon Ganymede, as well as the impact crater Nicholson on Mars have also been named after him.[2] The official naming citation was published by the Minor Planet Center on 15 October 1977 (M.P.C. 4236).[12]

Physical characteristicsEdit

In the SMASS classification, Nicholson is a common stony S-type asteroid.[3][5]

Rotation periodEdit

In April 2015, a rotational lightcurve of Nicholson was obtained from photometric observations by a group of Spanish astronomers from Valencia and Alicante at various observatories: (J08), (Z95), (J67), (Z98) and (I57). Lightcurve analysis gave a well-defined rotation period of 3.228±0.001 hours and a brightness variation of 0.24 magnitude (U=3).[9] At the same time, Serbian astronomer Vladimir Benishek at the Belgrade Observatory determined a concurring period of 3.25510±0.00003 hours with an amplitude of 0.29 magnitude (U=3).[13]

Diameter and albedoEdit

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Nicholson measures 7.1 and 8.1 kilometers in diameter and its surface has an albedo of 0.39 and 0.296, respectively.[6][7][8] The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.24 – derived from 8 Flora, the namesake of the Flora family – and calculates a diameter of 8.58 kilometers based on an absolute magnitude of 12.5.[5]


  1. ^ a b c d e "1831 Nicholson (1968 HC)". Minor Planet Center. Retrieved 7 December 2018.
  2. ^ a b c Schmadel, Lutz D. (2007). "(1831) Nicholson". Dictionary of Minor Planet Names – (1831) Nicholson. Springer Berlin Heidelberg. p. 147. doi:10.1007/978-3-540-29925-7_1832. ISBN 978-3-540-00238-3.
  3. ^ a b c d e f "JPL Small-Body Database Browser: 1831 Nicholson (1968 HC)" (2018-05-25 last obs.). Jet Propulsion Laboratory. Retrieved 7 December 2018.
  4. ^ a b c d "Asteroid 1831 Nicholson". Small Bodies Data Ferret. Retrieved 7 December 2018.
  5. ^ a b c d e f "LCDB Data for (1831) Nicholson". Asteroid Lightcurve Database (LCDB). Retrieved 7 December 2018.
  6. ^ 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.
  7. ^ 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". The Astrophysical Journal Letters. 759 (1): 5. arXiv:1209.5794. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8.
  8. ^ a b c d Mainzer, A. K.; Bauer, J. M.; Cutri, R. M.; Grav, T.; Kramer, E. A.; Masiero, J. R.; et al. (June 2016). "NEOWISE Diameters and Albedos V1.0". NASA Planetary Data System: EAR-A-COMPIL-5-NEOWISEDIAM-V1.0. Bibcode:2016PDSS..247.....M. Retrieved 7 December 2018.
  9. ^ a b Garcerà; n, Alfonso Carreñ; o; Macias, Amadeo Aznar; Mansego, Enrique Arce; Rodriguez, Pedro Brines; et al. (October 2015). "Lightcurve Analysis of Six Asteroids". The Minor Planet Bulletin. 42 (4): 235–237. Bibcode:2015MPBu...42..235G. ISSN 1052-8091. Retrieved 7 December 2018.
  10. ^ Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). Identification and Dynamical Properties of Asteroid Families. Asteroids IV. pp. 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. ISBN 9780816532131.
  11. ^ "Asteroid (1831) Nicholson – Proper elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 20 October 2019.
  12. ^ Schmadel, Lutz D. "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.
  13. ^ Benishek, Vladimir (January 2016). "Rotation Periods of 1831 Nicholson, 2929 Harris, 8463 Naomimurdoch, and (34173) 2000 QY37". The Minor Planet Bulletin. 43 (1): 89–90. Bibcode:2016MPBu...43...89B. ISSN 1052-8091. Retrieved 7 December 2018.

External linksEdit