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5477 Holmes, provisional designation 1989 UH2, is a Hungaria asteroid and binary system from the innermost regions of the asteroid belt, approximately 3 kilometers (2 miles) in diameter. It was discovered on 27 October 1989, by American astronomer Eleanor Helin at the Palomar Observatory in California.[1] The presumed E-type asteroid is likely spherical in shape and has a short rotation period of 2.99 hours.[3] It was named for American amateur astronomer Robert Holmes.[1] The discovery of its 1-kilometer-sized minor-planet moon was announced in November 2005.[5][6]

5477 Holmes
Discovery [1]
Discovered byE. F. Helin
Discovery sitePalomar Obs.
Discovery date27 October 1989
MPC designation(5477) Holmes
Named after
Robert Holmes[1]
(American astronomer)
1989 UH2
main-belt · (inner)[2]
Orbital characteristics[2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc27.60 yr (10,082 d)
Aphelion2.0613 AU
Perihelion1.7732 AU
1.9172 AU
2.65 yr (970 d)
0° 22m 16.68s / day
Known satellites1 (D: 1.09 km P: 24.4 h)[3][5][6]
Physical characteristics
Mean diameter
2.95±0.13 km (derived)[5]
3.147±0.137 km[7][8]
3.21 km (taken)[3]
3.215 km[9]
2.9932±0.0002 h[10][a]
2.9940±0.0002 h[11]
2.99401±0.00007 h[12]
2.99408±0.00007 h[13]
2.9943±0.0002 h[6]
E (assumed)[3]
13.99±0.03 (R)[12]


Orbit and classificationEdit

Holmes is a core member of the Hungaria family (003),[4] a large family of bright asteroids that forms the innermost dense concentration of asteroids in the Solar System, as the Mars-crosser and near-Earth populations are much more sparse. The family is part of the larger dynamical group with the same name.[1][3] It orbits the Sun in the innermost asteroid belt at a distance of 1.8–2.1 AU once every 2 years and 8 months (970 days; semi-major axis of 1.92 AU). Its orbit has an eccentricity of 0.08 and an inclination of 23° with respect to the ecliptic.[2] The body's observation arc begins with its official discovery observation at Palomar in October 1989.[1]

Physical characteristicsEdit

Holmes is an assumed E-type asteroid,[3] which agrees with the overall spectral type for members of the Hungaria family.[15]:23

Rotation periodEdit

Since 2005, several rotational lightcurves of Holmes have been obtained from photometric observations by Brian Warner and Petr Pravec in collaboration with other astronomers.[6][10][11][12][13][a] Analysis of the best-rated lightcurve gave a well-defined rotation period of 2.9940 hours with a consolidated brightness amplitude between 0.10 and 0.12 magnitude, which indicates that the body has a nearly spherical shape (U=3).[3][11] The asteroid's short period is near that of a fast rotator.

Diameter and albedoEdit

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), Holmes measures 3.147 kilometers in diameter and its surface has an albedo of 0.31,[7][8] while the Collaborative Asteroid Lightcurve Link adopts Petr Pravec's revised WISE-data, that is, an albedo of 0.2849 and a diameter of 3.21 kilometers based on an absolute magnitude of 14.445.[3][9] Johnston's Archive derives a diameter of 2.95 and 3.15 kilometers for the primary only and for the combined system, respectively.[5]


The photometric observations obtained by Brian Warner and collaborators during 2–12 November 2005,[13] revealed that Holmes is a synchronous binary asteroid with a minor-planet moon orbiting it every 24.4 hours at an estimated average distance of 6.7 km. The discovery was announced immediately on 15 November 2005.[6] The mutual occultation events indicated the presence of a satellite 37% the size of its primary, which translates into an estimated diameter of 1.09–1.19 kilometers depending on the underlying size estimate of the primary.[3][5]


This minor planet was named after American amateur astronomer Robert E. Holmes Jr (born 1956), who directs the Astronomical Research Observatory (H21) in Westfield, Illinois.[1] The official naming citation was suggested by Sergio Foglia and published by the Minor Planet Center on 18 February 2011 (M.P.C. 73983).[16]


  1. ^ a b Lightcurve plot of 5477 Holmes, Palmer Divide Observatory, Brian D. Warner (2012). Rotation period 2.9932±0.0002 hours with a brightness amplitude of 0.10±0.01 mag. The second plot for the orbital period of the satellite gives a period of 24.37±0.01 hours. Quality code is 3. Summary figures at the LCDB.


  1. ^ a b c d e f g h "5477 Holmes (1989 UH2)". Minor Planet Center. Retrieved 17 May 2018.
  2. ^ a b c d "JPL Small-Body Database Browser: 5477 Holmes (1989 UH2)" (2017-06-04 last obs.). Jet Propulsion Laboratory. Retrieved 17 May 2018.
  3. ^ a b c d e f g h i j k "LCDB Data for (5477) Holmes". Asteroid Lightcurve Database (LCDB). Retrieved 17 May 2018.
  4. ^ a b "Asteroid 5477 Holmes". Small Bodies Data Ferret. Retrieved 15 May 2018.
  5. ^ a b c d e Johnston, Wm. Robert (21 September 2014). "Asteroids with Satellites Database – (5477) Holmes". Johnston's Archive. Retrieved 17 May 2018.
  6. ^ a b c d e Warner, B. D.; Pravec, P.; Kusnirak, P.; Cooney, W.; Gross, J.; Terrell, D.; et al. (November 2005). "CBET #288 – (5477) 1989 UH_2". Central Bureau Electronic Telegrams. 288 (288): 1. Bibcode:2005CBET..288....1W. Retrieved 17 May 2018.
  7. ^ 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.
  8. ^ 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)
  9. ^ a b c d Pravec, Petr; Harris, Alan W.; Kusnirák, Peter; Galád, Adrián; Hornoch, Kamil (September 2012). "Absolute magnitudes of asteroids and a revision of asteroid albedo estimates from WISE thermal observations". Icarus. 221 (1): 365–387. Bibcode:2012Icar..221..365P. doi:10.1016/j.icarus.2012.07.026.
  10. ^ a b Warner, Brian D.; Stephens, Robert D.; Coley Daniel (October 2012). "Lightcurve for the Hungaria Binary 5477 Holmes". The Minor Planet Bulletin. 39 (4): 230–231. Bibcode:2012MPBu...39..230W. ISSN 1052-8091.
  11. ^ a b c Pravec, P.; Scheirich, P.; Kusnirák, P.; Hornoch, K.; Galád, A.; Naidu, S. P.; et al. (March 2016). "Binary asteroid population. 3. Secondary rotations and elongations". Icarus. 267: 267–295. Bibcode:2016Icar..267..267P. doi:10.1016/j.icarus.2015.12.019.
  12. ^ a b c Pravec, P.; Scheirich, P.; Vokrouhlický, D.; Harris, A. W.; Kusnirák, P.; Hornoch, K.; et al. (March 2012). "Binary asteroid population. 2. Anisotropic distribution of orbit poles of small, inner main-belt binaries". Icarus. 218 (1): 125–143. Bibcode:2012Icar..218..125P. doi:10.1016/j.icarus.2011.11.026.
  13. ^ a b c d Warner, Brian D.; Pravec, Petr; Kusnirak, Peter; Harris, Alan W.; Cooney, Walter R., Jr.; Gross, John; et al. (April 2011). "Lightcurves from the Initial Discovery of Four Hungaria Binary Asteroids". The Minor Planet Bulletin. 38 (2): 107–109. Bibcode:2011MPBu...38..107W. ISSN 1052-8091.
  14. ^ 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.
  15. ^ Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). Identification and Dynamical Properties of Asteroid Families. Asteroids IV. pp. 297–321. arXiv:1502.01628. doi:10.2458/azu_uapress_9780816532131-ch016. ISBN 9780816532131.
  16. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 17 May 2018.

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