1844 Susilva

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1844 Susilva
Discovery [1]
Discovered by P. Wild
Discovery site Zimmerwald Obs.
Discovery date 30 October 1972
MPC designation (1844) Susilva
Named after
Susi Petit–Pierre
(friend of discoverer)[2]
1972 UB · 1943 EU
1953 AA · 1959 GJ
main-belt · Eos[3]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc 64.40 yr (23,521 days)
Aphelion 3.1714 AU
Perihelion 2.8587 AU
3.0150 AU
Eccentricity 0.0518
5.24 yr (1,912 days)
0° 11m 17.88s / day
Inclination 11.788°
Physical characteristics
Dimensions 19.022±0.232 km[4]
22.41 km (calculated)[3]
26.800±0.321 km[5]
0.14 (assumed)[3]
10.8[4][5] · 11.0[1][3] · 11.49±0.44[6]

1844 Susilva, provisional designation 1972 UB, is a stony Eoan asteroid from the outer region of the asteroid belt, approximately 22 kilometers in diameter. It was discovered on 30 October 1972, by Swiss astronomer Paul Wild at Zimmerwald Observatory near Bern, Switzerland, and later named after a schoolfriend of the discoverer.[2][7]

Classification and orbit[edit]

Susilva is a member of the Eos family, a collisional group of more than 4,000 asteroids, which are well known for mostly being of silicaceous composition. It orbits the Sun in the outer main-belt at a distance of 2.9–3.2 AU once every 5 years and 3 months (1,912 days). Its orbit has an eccentricity of 0.05 and an inclination of 12° with respect to the ecliptic.[1] First identified as 1943 EU at Turku Observatory, Susilva's first used observation was taken at Uccle Observatory in 1953, extending the body's observation arc by 19 years prior to its official discovery observation.[7]

Physical characteristics[edit]

According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, the asteroid measures between 19.0 and 26.8 kilometers in diameter, and its surface has an albedo of 0.118 to 0.236.[4][5] The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.14, taken from 221 Eos, the family's largest member and namesake – and calculates a diameter of 22.4 kilometers based on an absolute magnitude of 11.0.[3] Susilva's rotation period has not yet been measured.[3]


The discoverer named a pair of asteroids after two of his former schoolmates, Susi and Helen, both from the small village of Wald, Zürich in Switzerland. This one was dedicated to Susi Petit–Pierre, while the subsequently numbered asteroid, 1845 Helewalda, was given to Helen Gachnang.[2][8] The approved naming citation was published by the Minor Planet Center before November 1977 (M.P.C. 4156).[9]


  1. ^ a b c d "JPL Small-Body Database Browser: 1844 Susilva (1972 UB)" (2017-06-05 last obs.). Jet Propulsion Laboratory. Retrieved 1 July 2017. 
  2. ^ a b c Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (1844) Susilva. Springer Berlin Heidelberg. p. 148. ISBN 978-3-540-00238-3. Retrieved 1 March 2016. 
  3. ^ a b c d e f g "LCDB Data for (1844) Susilva". Asteroid Lightcurve Database (LCDB). Retrieved 1 March 2016. 
  4. ^ 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:1109.6407Freely accessible. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. Retrieved 1 March 2016. 
  5. ^ 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 1 March 2016. 
  6. ^ 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 1 March 2016. 
  7. ^ a b "1844 Susilva (1972 UB)". Minor Planet Center. Retrieved 1 March 2016. 
  8. ^ "Himmlischer Besuch auf der Sternwarte Eschenberg" (in German). Sternwarte Eschenberg. Retrieved 1 March 2016. Helen Gachnang and Susi Petit-Pierre visit the Eschenberg Observatory 
  9. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 14 December 2016. 

External links[edit]