1689 Floris-Jan

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1689 Floris-Jan
Discovery [1]
Discovered by H. van Gent
Discovery site Johannesburg Obs.
(Leiden Southern Station)
Discovery date 16 September 1930
MPC designation (1689) Floris-Jan
Named after
Floris-Jan van der Meulen
(Contest Winner)[2]
1930 SO · 1926 PG
1928 DN · 1934 VV
1943 AC · 1949 OF
1949 ON1 · 1949 OY
1951 CW · 1966 BP
main-belt · (inner)[3]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc 89.19 yr (32,577 days)
Aphelion 2.9545 AU
Perihelion 1.9461 AU
2.4503 AU
Eccentricity 0.2058
3.84 yr (1,401 days)
0° 15m 25.2s / day
Inclination 6.3757°
Physical characteristics
Dimensions 13.743±1.905 km[4]
13.99±0.23 km[5]
16.122±4.950 km[6]
16.21 km (taken)[3]
16.213 km[7]
0.083 h (fragm.)[8]
144.85±0.20 h[9]
145 h[10]
B–V = 0.685[1]
U–B = 0.265[1]
11.74±0.05[3][7][9] · 11.79±0.19[11] · 11.82[1][4][5][6]

1689 Floris-Jan, provisional designation 1930 SO, is a stony asteroid and a slow rotator from the inner regions of the asteroid belt, approximately 16 kilometers in diameter. Discovered by Hendrik van Gent in 1930, it was named after a contest winner of an exhibition at Leiden Observatory.


It was discovered on 16 September 1930, by Dutch astronomer Hendrik van Gent at the Leiden Southern Station, annex to the Johannesburg Observatory in South Africa.[12] It was independently discovered by Soviet astronomer Evgenii Skvortsov at the Crimean Simeiz Observatory five days later.[2]

Orbit and classification[edit]

Floris-Jan orbits the Sun in the inner main-belt at a distance of 1.9–3.0 AU once every 3 years and 10 months (1,401 days). Its orbit has an eccentricity of 0.21 and an inclination of 6° with respect to the ecliptic.[1] First identified as 1926 PG at Simeiz Observatory in 1926, the body's observation arc begins 3 days after its official discovery observation at Johannesburg in 1930.[12]

Physical characteristics[edit]

Slow rotator[edit]

In the 1980s, photometric lightcurve observations already revealed that Floris-Jan is a very slow rotator with a rotation period of 145 hours and a brightness variation of 0.4 magnitude (U=3).[10] At the time, this six-day period was a new record among all minor planets with a known rotation period, and it was assumed, that Floris-Jan might also be a tumbling asteroid with a non-principal axis rotation.[3][9]

Diameter and albedo[edit]

According to the surveys carried out by the Japanese Akari satellite and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Floris-Jan measures between 13.74 and 16.12 kilometers in diameter, and its surface has an albedo between 0.127 and 0.184.[4][5][6] The Collaborative Asteroid Lightcurve Link agrees with Petr Pravec's revised WISE-data, that is an albedo of 0.135 and a diameter of 16.21 kilometers based on an absolute magnitude of 11.74.[3]


This minor planet was named for Floris-Jan van der Meulen, the 5,000th visitor to a 14-day astronomical exhibition at the Leiden Observatory.[2] The official naming citation was published by the Minor Planet Center before November 1977 (M.P.C. 3470).[13]


  1. ^ a b c d e f "JPL Small-Body Database Browser: 1689 Floris-Jan (1930 SO)" (2017-05-05 last obs.). Jet Propulsion Laboratory. Retrieved 6 June 2017. 
  2. ^ a b c Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (1689) Floris-Jan. Springer Berlin Heidelberg. p. 134. ISBN 978-3-540-00238-3. Retrieved 22 December 2016. 
  3. ^ a b c d e f "LCDB Data for (1689) Floris-Jan". Asteroid Lightcurve Database (LCDB). Retrieved 22 December 2016. 
  4. ^ 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:1209.5794Freely accessible. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8. Retrieved 22 December 2016. 
  5. ^ 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 22 December 2016. 
  6. ^ 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" (PDF). The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407Freely accessible. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. Retrieved 22 December 2016. 
  7. ^ a b c 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. Retrieved 22 December 2016. 
  8. ^ Pych, W. (March 1999). "Short period oscillations in the light curve of the asteroid 1689 Floris-Jan". Astronomy and Astrophysics: L75–L77. arXiv:astro-ph/9806384Freely accessible. Bibcode:1999A&A...343L..75P. Retrieved 22 December 2016. 
  9. ^ a b c Harris, A. W.; Young, J. W. (October 1989). "Asteroid lightcurve observations from 1979-1981". Icarus: 314–364. Bibcode:1989Icar...81..314H. doi:10.1016/0019-1035(89)90056-0. ISSN 0019-1035. Retrieved 22 December 2016. 
  10. ^ a b Schober, H. J.; Surdej, J.; Harris, A. W.; Young, J. W. (November 1982). "The six-day rotation period of 1689 Floris-Jan - A new record among slowly rotating asteroids". Astronomy and Astrophysics: 257–262.ResearchsupportedbytheOsterreichischerFondszurForderungderwissenschaftlichenForschung. Bibcode:1982A&A...115..257S. Retrieved 22 December 2016. 
  11. ^ 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:1506.00762Freely accessible. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 22 December 2016. 
  12. ^ a b "1689 Floris-Jan (1930 SO)". Minor Planet Center. Retrieved 22 December 2016. 
  13. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 22 December 2016. 

External links[edit]