1938 Lausanna

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1938 Lausanna
Discovery [1]
Discovered by P. Wild
Discovery site Zimmerwald Obs.
Discovery date 19 April 1974
MPC designation (1938) Lausanna
Named after
Lausanne (Swiss city)[2]
1974 HC · 1934 KA
1947 DB · 1950 CO
1955 VK · 1957 EH
1962 WB1 · 1967 ED1
1971 OX · 1972 XY1
main-belt · Flora[3]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc 82.99 yr (30,312 days)
Aphelion 2.5938 AU
Perihelion 1.8796 AU
2.2367 AU
Eccentricity 0.1597
3.35 yr (1,222 days)
0° 17m 40.56s / day
Inclination 3.3343°
Physical characteristics
Dimensions 7.638±0.124 km[4]
7.82 km (calculated)[3]
8.214±0.077 km[5]
2.748±0.001 h[a]
2.748±0.001 h[6]
0.24 (assumed)[3]
12.60±0.26[7] · 12.7[1][3] · 13.0[5]

1938 Lausanna, provisional designation 1974 HC, is a stony Florian asteroid from the inner regions of the asteroid belt, approximately 8 kilometers in diameter. It was discovered on 19 April 1974, by Swiss astronomer Paul Wild at Zimmerwald Observatory near Bern, Switzerland.[8] It is named for the city of Lausanne.[2]

Orbit and classification[edit]

Lausanna is a S-type asteroid and member of the Flora family, one of the largest collisional populations of stony asteroids in the main-belt. It orbits the Sun in the inner main-belt at a distance of 1.9–2.6 AU once every 3 years and 4 months (1,222 days). Its orbit has an eccentricity of 0.16 and an inclination of 3° with respect to the ecliptic.[1] It was first identified as 1934 KA at Johannesburg Observatory in 1934, extending the body's observation arc by 40 years prior to its official discovery observation at Zimmerwald.[8]

Physical characteristics[edit]

Rotation period[edit]

In March 2014, two rotational lightcurves of Lausanna were obtained from photometric observations by American astronomer Brian Skiff and by Johan Warell at Lindby Observatory (K60) in Sweden. Lightcurve analysis gave an identical rotation period of 2.748 hours with a brightness amplitude of 0.13 and 0.12 magnitude, respectively (U=3-/2).[a][6] The short period is near the threshold of 2.2 hours for fast rotating asteroids.

Diameter and albedo[edit]

According to the space-based survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Lausanna measures 7.64 and 8.21 kilometers in diameter, and its surface has an albedo of 0.166 and 0.192, respectively.[4][5] The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.24 – derived from 8 Flora, the largest member and namesake of its family – and calculates a diameter of 7.82 kilometers based on an absolute magnitude of 12.7.[3]


This minor planet was named for the Swiss city of Lausanne, located in the French-speaking part of the country. The discoverer Paul Wild, known for his unconventional minor-planet namings, discovered three more asteroids during winter of 1973/74. He named these 1935 Lucerna, 1936 Lugano and 1937 Locarno, after the Swiss cities Lucerne, Lugano and Locarno, respectively, hence composing an alliterated quartet of sequentially numbered, thematically named minor planets. The official naming citation was published by the Minor Planet Center before November 1977 (M.P.C. 4358).[9]


  1. ^ a b Skiff (2014) web: rotation period 2.748±0.001 hours with a brightness amplitude of 0.13 mag and a Quality Code of 3-. Summary figures at Collaborative Asteroid Lightcurve Link (CALL) for (1938) Lausanna


  1. ^ a b c d "JPL Small-Body Database Browser: 1938 Lausanna (1974 HC)" (2017-05-06 last obs.). Jet Propulsion Laboratory. Retrieved 10 June 2017. 
  2. ^ a b Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (1938) Lausanna. Springer Berlin Heidelberg. p. 155. ISBN 978-3-540-00238-3. Retrieved 26 January 2017. 
  3. ^ a b c d e f "LCDB Data for (1938) Lausanna". Asteroid Lightcurve Database (LCDB). Retrieved 26 January 2017. 
  4. ^ 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 26 January 2017. 
  5. ^ 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 26 January 2017. 
  6. ^ a b Warell, Johan; Pappini, Riccardo (January 2015). "Rotational Period of 1938 Lausanna". The Minor Planet Bulletin. 42 (1): 20–21. Bibcode:2015MPBu...42...20W. ISSN 1052-8091. Retrieved 26 January 2017. 
  7. ^ a b 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 26 January 2017. 
  8. ^ a b "1938 Lausanna (1974 HC)". Minor Planet Center. Retrieved 26 January 2017. 
  9. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 26 January 2017. 

External links[edit]