1541 Estonia

1541 Estonia, provisional designation 1939 CK, is an asteroid from the central regions of the asteroid belt, approximately 21 kilometers in diameter. It was discovered on 12 February 1939, by astronomer Yrjö Väisälä at the Iso-Heikkilä Observatory near Turku, Finland.[11] The asteroid was named after the Baltic country of Estonia.[2]

1541 Estonia
Discovery [1]
Discovered byY. Väisälä
Discovery siteTurku Obs.
Discovery date12 February 1939
Designations
(1541) Estonia
Named after
Estonia [2]
(Baltic country)
1939 CK · 1930 FE
1930 FV · 1950 RG1
1950 SR · 1959 RF1
A916 GE · A923 VE
main-belt · (middle)
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc93.57 yr (34,176 days)
Aphelion2.9610 AU
Perihelion2.5761 AU
2.7685 AU
Eccentricity0.0695
4.61 yr (1,683 days)
346.22°
0° 12m 50.4s / day
Inclination4.8750°
1.4553°
192.84°
Physical characteristics
Dimensions19.53±0.40 km[3]
20.15 km (derived)[4]
20.56±6.71 km[5]
22.000±0.342 km[6]
23.89±1.35 km[7]
24.542±0.096 km[8]
10.1±1.0 h[9]
0.0976±0.0129[8]
0.104±0.012[7]
0.12±0.13[5]
0.1314 (derived)[4]
0.140±0.016[3]
SMASS = Xc [1] · X [4]
11.20[7][8] · 11.30[4][3][5] · 11.4[1] · 11.56±0.24[10]

    Orbit and classification

    Estonia is a non-family asteroid from the main belt's background population. It orbits the Sun in the central main belt at a distance of 2.6–3.0 AU once every 4 years and 7 months (1,683 days). Its orbit has an eccentricity of 0.07 and an inclination of 5° with respect to the ecliptic.[1]

    The asteroid was first identified as A916 GE at the Simeiz Observatory in April 1916. The body's observation arc begins with its identification as A923 VE at Yerkes Observatory in November 1923, more than 15 years prior to its official discovery observation at Turku.[11]

    Physical characteristics

    In the SMASS classification, Estonia is a Xc-subtype that transitions from the X-type to the carbonaceous C-type asteroids.[1]

    Rotation period

    In November 2015, a rotational lightcurve of Estonia was obtained from photometric observations by French amateur astronomer René Roy. Lightcurve analysis gave a rotation period of 10.1 hours with a brightness amplitude of 0.13 magnitude (U=2-).[9]

    Diameter and albedo

    According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Estonia measures between 19.53 and 24.542 kilometers in diameter and its surface has an albedo between 0.0976 and 0.140.[3][5][6][7][8]

    The Collaborative Asteroid Lightcurve Link derives an albedo of 0.1314 and a diameter of 20.15 kilometers based on an absolute magnitude of 11.3.[4]

    Naming

    This minor planet was named after the Baltic country of Estonia, just south of the Gulf of Finland and Finland itself. Historically, both countries have been inhabited by Finno-Ugric people. Estonia gained independence from Soviet rule in 1991.[2] The official naming citation was published by the Minor Planet Center in January 1956 (M.P.C. 1350).[12]

    References
    1. "JPL Small-Body Database Browser: 1541 Estonia (1939 CK)" (2017-06-04 last obs.). Jet Propulsion Laboratory. Retrieved 20 September 2017.
    2. Schmadel, Lutz D. (2007). "(1541) Estonia". Dictionary of Minor Planet Names – (1541) Estonia. Springer Berlin Heidelberg. p. 122. doi:10.1007/978-3-540-29925-7_1542. ISBN 978-3-540-00238-3.
    3. 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. Retrieved 20 September 2017.
    4. "LCDB Data for (1541) Estonia". Asteroid Lightcurve Database (LCDB). Retrieved 20 September 2017.
    5. 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:1509.02522. Bibcode:2015ApJ...814..117N. doi:10.1088/0004-637X/814/2/117. Retrieved 20 September 2017.
    6. 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:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121. Retrieved 20 September 2017.
    7. 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 17 October 2019. (online, AcuA catalog p. 153)
    8. 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.
    9. Behrend, Raoul. "Asteroids and comets rotation curves – (1541) Estonia". Geneva Observatory. Retrieved 20 September 2017.
    10. 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. Retrieved 20 September 2017.
    11. "1541 Estonia (1939 CK)". Minor Planet Center. Retrieved 20 September 2017.
    12. Schmadel, Lutz D. (2009). "Appendix – Publication Dates of the MPCs". Dictionary of Minor Planet Names – Addendum to Fifth Edition (2006–2008). Springer Berlin Heidelberg. p. 221. doi:10.1007/978-3-642-01965-4. ISBN 978-3-642-01964-7.

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