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3391 Sinon (/ˈsnɒn/ SY-non), provisional designation 1977 DD3, is a mid-sized Jupiter trojan from the Greek camp, approximately 40 kilometers (25 miles) in diameter. It was discovered on 18 February 1977, by Japanese astronomers Hiroki Kosai and Kiichirō Furukawa at the Kiso Observatory in Japan.[1] The dark Jovian asteroid has a rotation period of 8.1 hours and likely an elongated shape.[6] It was named after the hero Sinon from Greek mythology.[1]

3391 Sinon
Discovery [1]
Discovered byH. Kosai
K. Furukawa
Discovery siteKiso Station
Discovery date18 February 1977
MPC designation(3391) Sinon
Pronunciation/ˈsnɒn/ · SY-non
Named after
Sinon (Greek mythology)[1]
1977 DD3
Jupiter trojan[1][2]
Greek[3] · background[4]
Orbital characteristics[2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc63.16 yr (23,071 d)
Aphelion5.7383 AU
Perihelion4.8691 AU
5.3037 AU
12.21 yr (4,461 d)
0° 4m 50.52s / day
Jupiter MOID0.2572 AU
Physical characteristics
Mean diameter
37.86±6.82 km[5]
48.48 km (calculated)[6]
8.135 h[7][a]
0.057 (assumed)[6]
C (assumed)[6]

Orbit and classificationEdit

Sinon is a dark Jovian asteroid in a 1:1 orbital resonance with Jupiter. It is located in the leading Greek camp at the Gas Giant's L4 Lagrangian point, 60° ahead on its orbit (see Trojans in astronomy).[3] It is also a non-family asteroid of the Jovian background population.[4] It orbits the Sun at a distance of 4.9–5.7 AU once every 12 years and 3 months (4,461 days; semi-major axis of 5.3 AU). Its orbit has an eccentricity of 0.08 and an inclination of 15° with respect to the ecliptic.[2] The body's observation arc begins with a precovery at Palomar Observatory in March 1953, almost 24 years prior to its official discovery observation at Kiso.[1]

Physical characteristicsEdit

Sinon is an assumed, carbonaceous C-type asteroid.[6]

Rotation periodEdit

In February 2013, a rotational lightcurve of Sinon was obtained from photometric observations by Lawrence Wasserman at Lowell Observatory and by Robert Stephens at the Center for Solar System Studies. Lightcurve analysis gave a well-defined rotation period of 8.135±0.002 hours with a brightness amplitude of 0.72 magnitude, indicative of a non-spherical shape (U=3).[6][7][a]

Diameter and albedoEdit

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Sinon measures 37.86 kilometers in diameter and its surface has an albedo of 0.093,[5] while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for a carbonaceous asteroid of 0.057 and calculates a diameter of 48.48 kilometers based on an absolute magnitude of 10.3.[6]


This minor planet was named from Greek mythology after Sinon, a Greek warrior of the Trojan War.[1] The official naming citation was published by the Minor Planet Center on 16 December 1986 (M.P.C. 11443).[8]


  1. ^ a b Lightcurve plot of (3391) Sinon from Feb 2013 by Robert Stephens at the Center for Solar System Studies (U81). Quality code is not available (lightcurve rating at CS3). Summary figures at the LCDB and CS3.


  1. ^ a b c d e f g h "3391 Sinon (1977 DD3)". Minor Planet Center. Retrieved 20 June 2018.
  2. ^ a b c d "JPL Small-Body Database Browser: 3391 Sinon (1977 DD3)" (2018-05-23 last obs.). Jet Propulsion Laboratory. Retrieved 20 June 2018.
  3. ^ a b "List of Jupiter Trojans". Minor Planet Center. 1 June 2018. Retrieved 20 June 2018.
  4. ^ a b "Asteroid (3391) Sinon – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 20 June 2018.
  5. ^ a b c d Grav, T.; Mainzer, A. K.; Bauer, J. M.; Masiero, J. R.; Nugent, C. R. (November 2012). "WISE/NEOWISE Observations of the Jovian Trojan Population: Taxonomy". The Astrophysical Journal. 759 (1): 10. arXiv:1209.1549. Bibcode:2012ApJ...759...49G. doi:10.1088/0004-637X/759/1/49. Retrieved 20 June 2018. (online catalog)
  6. ^ a b c d e f g h "LCDB Data for (3391) Sinon". Asteroid Lightcurve Database (LCDB). Retrieved 20 June 2018.
  7. ^ a b French, Linda M.; Stephens, Robert, D.; Coley, Daniel R.; Wasserman, Lawrence H.; Vilas, Faith; La Rocca, Daniel (October 2013). "A Troop of Trojans: Photometry of 24 Jovian Trojan Asteroids". The Minor Planet Bulletin. 40 (4): 198–203. Bibcode:2013MPBu...40..198F. ISSN 1052-8091. Retrieved 20 June 2018.
  8. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 20 June 2018.

External linksEdit