(6265) 1985 TW3

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(6265) 1985 TW3
Discovery [1]
Discovered byT. F. Fric
R. J. Gilbrech
Discovery sitePalomar Obs.
Discovery date11 October 1985
MPC designation(6265) 1985 TW3
1985 TW3 · 1953 RK1
1969 TZ4 · 1979 YG9
1985 VQ1 · 1987 GD1
1990 CX
main-belt[1][2] · (inner)
Orbital characteristics[2]
Epoch 27 April 2019 (JD 2458600.5)
Uncertainty parameter 0
Observation arc48.42 yr (17,685 d)
Aphelion2.5839 AU
Perihelion1.7476 AU
2.1658 AU
3.19 yr (1,164 d)
0° 18m 33.12s / day
Known satellites1 (D: 1.16 km; P: 15.9 h)[4][5]
Physical characteristics
Mean diameter
4.954±0.100 km[6][7][8]
5.20±0.22 km[9]
2.70932±0.00008 h[10]
L (SDSS-MOC)[11]

(6265) 1985 TW3, provisional designation 1985 TW3, is a background asteroid and binary system from the inner regions of the asteroid belt. It was discovered on 11 October 1985, by astronomer by T. F. Fric and Richard Gilbrech at the Palomar Observatory in California. It is the only minor-planet discovery for these two astronomers.[1] The stony L-type asteroid measures approximately 5 kilometers (3.1 miles) in diameter and has a rotation period of 2.7 hours.[12] Its 1.2-kilometer sized minor-planet moon was discovered in July 2007 and announced the following month.[4]

Orbit and classification[edit]

1985 TW3 is a non-family asteroid from the main belt's background population when applying the hierarchical clustering method to its proper orbital elements.[3] Based on osculating Keplerian orbital elements, the asteroid has also been classified as a member of the Flora family (402), a giant asteroid family and the largest family of stony asteroids in the main-belt.[12]

It orbits the Sun in the inner asteroid belt at a distance of 1.7–2.6 AU once every 3 years and 2 months (1,164 days; semi-major axis of 2.17 AU). Its orbit has an eccentricity of 0.19 and an inclination of 4° with respect to the ecliptic.[2] It was first observed as 1953 RK1 at the former Alma-Ata Observatory (210) in September 1953. The body's observation arc begins with its observation as 1979 YG9 at Crimea–Nauchnij in December 1979, or almost 6 years prior to its official discovery observation at Palomar Observatory.[1]

Numbering and naming[edit]

This minor planet was permanently numbered (6265) by the Minor Planet Center on 17 March 1995 (M.P.C. 24890–24891).[13] As of 2018, it has not been named.[1]

Physical characteristics[edit]

In the SDSS-based taxonomy, 1985 TW3 is an unusual L-type asteroid.[11]

Rotation period[edit]

In June 2010, a rotational lightcurve of 1985 TW3 was obtained from photometric observations by Australian astronomers David Higgins and Julian Oey at the Hunters Hill (E14) and Leura Observatory (E17). Lightcurve analysis gave a well-defined rotation period of 2.70932±0.00008 hours with a brightness variation of 0.35 magnitude (U=3).[10] Several concurring period determinations in the range of 2.7091 to 2.710 hours with an amplitude of 0.26 to 0.36 magnitude were also made between 2007 and 2013 (U=3/3/3/3-/2).[14][5][15][16][17]


During a previous photometric observation by David Higgins on 15 July 2007, it was revealed that 1985 TW3 is a binary asteroid with a minor-planet moon in its orbit. The discovery was announced on 2 August 2007.[5] The satellite, provisional designation S/2007 (6265) 1, measures approximately 1.16 kilometers. It is separated by 8 km from its primary, orbiting it once every 15 hours and 52 minutes (15.859 hours or 0.6608 days).[4]

Diameter and albedo[edit]

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), 1985 TW3 measures between 4.95 and 5.20 kilometers in diameter and its surface has an albedo between 0.285 and 0.287.[6][7][8][9] The Johnston's archive derives a diameter of 4.81 km and 1.16 km for the primary and secondary, respectively, based on an effective WISE-diameter of 4.95 km and using the lower limit of 0.24 for the secondary-to-primary diameter-ratio (Ds/p) determined by David Higgins.[4][5] Later observation by Higgins and Pravec determined a Ds/p ratio of 0.30 to 0.32,[10][15] which increases the satellites size by a quarter to a third if all other factors remain unchanged. The Collaborative Asteroid Lightcurve Link assumes a standard albedo for members of the Flora family of 0.24 and calculates a diameter of 5.17 kilometers based on an absolute magnitude of 13.6.[12]


  1. ^ a b c d e f "6265 (1985 TW3)". Minor Planet Center. Retrieved 26 November 2018.
  2. ^ a b c d "JPL Small-Body Database Browser: 6265 (1985 TW3)" (2018-03-16 last obs.). Jet Propulsion Laboratory. Retrieved 26 November 2018.
  3. ^ a b "Asteroid (6265) 1985 TW3". Small Bodies Data Ferret. Retrieved 26 November 2018.
  4. ^ a b c d Johnston, Wm. Robert (21 September 2014). "Asteroids with Satellites Database – (6265) 1985 TW3". Johnston's Archive. Retrieved 26 November 2018.
  5. ^ a b c d Higgins, D.; Pravec, P.; Kusnirak, P. (August 2007). "(6265) 1985 TW3". Central Bureau Electronic Telegrams. 1015 (1015): 1. Bibcode:2007CBET.1015....1H. Retrieved 26 November 2018.
  6. ^ 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 26 November 2018.
  7. ^ a b 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 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.
  10. ^ a b c Higgins, David; Oey, Julian; Pravec, Petr (January 2011). "Period Determination of Binary Asteroid Targets Observed at Hunters Hill Observatory: May-September 2009". The Minor Planet Bulletin. 38 (1): 46–49. Bibcode:2011MPBu...38...46H. ISSN 1052-8091.
  11. ^ a b Carvano, J. M.; Hasselmann, P. H.; Lazzaro, D.; Mothé-Diniz, T. (February 2010). "SDSS-based taxonomic classification and orbital distribution of main belt asteroids". Astronomy and Astrophysics. 510: 12. Bibcode:2010A&A...510A..43C. doi:10.1051/0004-6361/200913322. Retrieved 26 November 2018.
  12. ^ a b c d "LCDB Data for (6265)". Asteroid Lightcurve Database (LCDB). Retrieved 26 November 2018.
  13. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 26 November 2018.
  14. ^ Bianchi, E. (December 1920). "Osservazioni fotometriche di pianeti". Memorie della Società Astronomia Italiana. 2: 45. Bibcode:1921MmSAI...2...45B.
  15. ^ a b 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.
  16. ^ Oey, Julian (October 2014). "Lightcurve Analysis of Asteroids from Blue Mountains Observatory in 2013". The Minor Planet Bulletin. 41 (4): 276–281. Bibcode:2014MPBu...41..276O. ISSN 1052-8091.
  17. ^ 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". The Astronomical Journal. 150 (3): 35. arXiv:1504.04041. Bibcode:2015AJ....150...75W. doi:10.1088/0004-6256/150/3/75.

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