1520 Imatra

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1520 Imatra
Discovery [1]
Discovered by Y. Väisälä
Discovery site Turku Obs.
Discovery date 22 October 1938
MPC designation (1520) Imatra
Named after
Imatra (Finnish town)[2]
1938 UY · 1938 YH
main-belt · (outer)[3]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc 78.53 yr (28,682 days)
Aphelion 3.4132 AU
Perihelion 2.8113 AU
3.1123 AU
Eccentricity 0.0967
5.49 yr (2,005 days)
0° 10m 46.2s / day
Inclination 15.241°
Physical characteristics
Dimensions 53.41 km (derived)[3]
53.42±19.70 km[5]
53.435±0.370 km[6]
53.61±1.4 km[7]
53.79±14.73 km[8]
55.55±0.60 km[9]
56.094±1.824 km[10]
58.63±0.70 km[11]
5.23 h (dated)[12]
18.609±0.004 h[13]
18.635±0.004 h[14]
0.0428 (derived)[3]
SMASS = C[1] · C[3]
10.0[7][9][10] · 10.30[8][11] · 10.40±0.35[15] · 10.4[1][3] · 10.43[5]

1520 Imatra, provisional designation 1938 UY, is a carbonaceous Ursula asteroid from the outer region of the asteroid belt, approximately 54 kilometers in diameter. It was discovered on 22 October 1938, by Finnish astronomer Yrjö Väisälä at Turku Observatory in Southwest Finland, who named after the Finnish town of Imatra.[2][16]


Imatra is a member of the Ursula family (631),[4] a large family of C- and X-type asteroids, named after its parent body, 375 Ursula.[17]:23 It orbits the Sun in the outer main-belt at a distance of 2.8–3.4 AU once every 5 years and 6 months (2,005 days; semi-major axis of 3.11 AU). Its orbit has an eccentricity of 0.10 and an inclination of 15° with respect to the ecliptic.[1] No precoveries and no prior identifications were made. Imatra's observation arc begins at Turku, 3 weeks after its official discovery observation.[16]

Physical characteristics[edit]

Imatra is a C-type asteroid in the SMASS taxonomy.[1]

Rotation period[edit]

In July 2008, American astronomer Brian Warner obtained a rotational lightcurve of Imatra at his Palmer Divide Observatory in Colorado. It gave a rotation period of 18.635 hours with a brightness variation of 0.28 magnitude (U=3-),[14] superseding a period of 5.23 hours from observations at Italian and French observatories in the 1990s (U=2).[12] In September 2014, photometric observations by French amateur astronomers Laurent Bernasconi, Romain Montaigut and Arnaud Leroy gave a period of 18.609 hours with an amplitude of 0.27 magnitude (U=2+).[13]

Diameter and albedo[edit]

According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite, and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Imatra measures between 53.42 and 58.63 kilometers in diameter, and its surface has an albedo between 0.039 and 0.062.[5][6][7][8][9][10][11] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0428 and a diameter of 53.41 kilometers using an absolute magnitude of 10.4.[3]


This minor planet is named for the south-eastern Finnish town Imatra, located in South Karelia near the Russian border, about half way in between St Petersburg and Finland's capital Helsinki.[2] The official naming citation was published by the Minor Planet Center before November 1977 (M.P.C. 3929).[18]


  1. ^ a b c d e f "JPL Small-Body Database Browser: 1520 Imatra (1938 UY)" (2017-05-02 last obs.). Jet Propulsion Laboratory. Retrieved 5 June 2017. 
  2. ^ a b c Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (1520) Imatra. Springer Berlin Heidelberg. p. 121. ISBN 978-3-540-00238-3. Retrieved 3 January 2017. 
  3. ^ a b c d e f "LCDB Data for (1520) Imatra". Asteroid Lightcurve Database (LCDB). Retrieved 3 January 2017. 
  4. ^ a b "Small Bodies Data Ferret". Nesvorny HCM Asteroid Families V3.0. Retrieved 6 December 2017. 
  5. ^ 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:1606.08923Freely accessible. Bibcode:2016AJ....152...63N. doi:10.3847/0004-6256/152/3/63. Retrieved 3 January 2017. 
  6. ^ a b c Masiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. (August 2014). "Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos". The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645Freely accessible. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121. Retrieved 3 January 2017. 
  7. ^ a b c d Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System. Bibcode:2004PDSS...12.....T. Retrieved 3 January 2017. 
  8. ^ a b c d Nugent, C. R.; Mainzer, A.; Masiero, J.; Bauer, J.; Cutri, R. M.; Grav, T.; et al. (December 2015). "NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos". The Astrophysical Journal. 814 (2): 13. arXiv:1509.02522Freely accessible. Bibcode:2015ApJ...814..117N. doi:10.1088/0004-637X/814/2/117. Retrieved 3 January 2017. 
  9. ^ 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 3 January 2017. 
  10. ^ 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 3 January 2017. 
  11. ^ 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 3 January 2017. 
  12. ^ a b de Sanctis, M. C.; Barucci, M. A.; Angeli, C. A.; Fulchignoni, M.; Burchi, R.; Angelini, P. (October 1994). "Photoelectric and CCD observations of 10 asteroids". Planetary and Space Science: 859–864. Bibcode:1994P&SS...42..859D. doi:10.1016/0032-0633(94)90066-3. ISSN 0032-0633. Retrieved 3 January 2017. 
  13. ^ a b Behrend, Raoul. "Asteroids and comets rotation curves – (1520) Imatra". Geneva Observatory. Retrieved 3 January 2017. 
  14. ^ a b Warner, Brian D. (January 2009). "Asteroid Lightcurve Analysis at the Palmer Divide Observatory: 2008 May - September". The Minor Planet Bulletin. 36 (1): 7–13. Bibcode:2009MPBu...36....7W. ISSN 1052-8091. Retrieved 3 January 2017. 
  15. ^ 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 3 January 2017. 
  16. ^ a b "1520 Imatra (1938 UY)". Minor Planet Center. Retrieved 3 January 2017. 
  17. ^ Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). "Identification and Dynamical Properties of Asteroid Families" (PDF). Asteroids IV: 297–321. arXiv:1502.01628Freely accessible. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. Retrieved 6 December 2017. 
  18. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 3 January 2017. 

External links[edit]