1393 Sofala

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1393 Sofala
Discovery [1]
Discovered by C. Jackson
Discovery site Johannesburg Obs.
Discovery date 25 May 1936
MPC designation (1393) Sofala
Named after
(Province in Mozambique)[2]
1936 KD · 1928 FB
1951 GL · 1956 TE
1958 CA · 1971 SJ
1975 UB
main-belt · (inner)
Vestian[3] · background [4]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc 89.54 yr (32,703 days)
Aphelion 2.6997 AU
Perihelion 2.1685 AU
2.4341 AU
Eccentricity 0.1091
3.80 yr (1,387 days)
0° 15m 34.2s / day
Inclination 5.8476°
Physical characteristics
Dimensions 11.214±0.495 km[5]
11.30 km (calculated)[3]
7.8 h (poor)[6]
16.5931±0.0005 h[7]
108.259±0.7031 h[8]
0.20 (assumed)[3]
S (assumed)[3]
11.835±0.002 (R)[8] · 12.00[5] · 12.1[1][3] · 12.42±0.78[9]

1393 Sofala, provisional designation 1936 KD, is a Vestian asteroid from the inner regions of the asteroid belt, approximately 11 kilometers in diameter. It was discovered on 25 May 1936, by South African astronomer Cyril Jackson at the Union Observatory in Johannesburg.[10] The asteroid was named after the province of Sofala in Mozambique.[2]

Orbit and classification[edit]

Sofala is a member of the Vesta family (401),[3] the second-largest asteroid family of the main-belt by number of members. However, it is also considered to be a non-family asteroid of the main belt's background population when applying the Hierarchical Clustering Method to its proper orbital elements.[4] It orbits the Sun in the inner asteroid belt at a distance of 2.2–2.7 AU once every 3 years and 10 months (1,387 days). Its orbit has an eccentricity of 0.11 and an inclination of 6° with respect to the ecliptic.[1]

The asteroid was first identified as 1928 FB at Heidelberg Observatory in March 1928. The body's observation arc begins with its official discovery observation at Johannesburg in 1936.[10]

Physical characteristics[edit]

Sofala is an assumed stony S-type asteroid.[3]

Rotation period[edit]

The asteroid has an ambiguous lightcurve. While a lightcurve, obtained at the Palomar Transient Factory in September 2013, gave a rotation period of 108.259 hours with a brightness amplitude of 0.48 magnitude (U=2),[8] another lightcurve modeled from combined dense and sparse photometry gave a sidereal period of 16.5931 hours.(U=2).[7] If the first result were correct, Sofala would be one of few hundred known slow rotators with a period above 100 hours. The Lightcurve Data Base, however, adopts the shorter period from the modeled lightcurve.[3] A third lightcurve with a period of 7.8 hours by René Roy from 2008 has received a poor rating.[6]

Diameter and albedo[edit]

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Sofala measures between 11.21 kilometers in diameter and its surface has an albedo of 0.223.[5]

The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 11.30 kilometers based on an absolute magnitude of 12.1.[3]


This minor planet was named after Sofala Province in central-eastern Mozambique. It is the country's largest province.[2] Its capital city is Beira after which the Mars-crosser 1474 Beira, another discovery by Cyril Jackson, is named. The official naming citation was published by the Minor Planet Center before November 1977 (M.P.C. 909).[11]


  1. ^ a b c d "JPL Small-Body Database Browser: 1393 Sofala (1936 KD)" (2017-09-29 last obs.). Jet Propulsion Laboratory. Retrieved 24 October 2017. 
  2. ^ a b c Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (1393) Sofala. Springer Berlin Heidelberg. p. 113. ISBN 978-3-540-00238-3. Retrieved 24 October 2017. 
  3. ^ a b c d e f g h i "LCDB Data for (1393) Sofala". Asteroid Lightcurve Database (LCDB). Retrieved 24 October 2017. 
  4. ^ a b "Small Bodies Data Ferret". Nesvorny HCM Asteroid Families V3.0. Retrieved 24 October 2017. 
  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 24 October 2017. 
  6. ^ a b Behrend, Raoul. "Asteroids and comets rotation curves – (1393) Sofala". Geneva Observatory. Retrieved 24 October 2017. 
  7. ^ a b Hanus, J.; Durech, J.; Broz, M.; Marciniak, A.; Warner, B. D.; Pilcher, F.; et al. (March 2013). "Asteroids' physical models from combined dense and sparse photometry and scaling of the YORP effect by the observed obliquity distribution" (PDF). Astronomy and Astrophysics. 551: 16. arXiv:1301.6943Freely accessible. Bibcode:2013A&A...551A..67H. doi:10.1051/0004-6361/201220701. Retrieved 24 October 2017. 
  8. ^ a b c Waszczak, Adam; Chang, Chan-Kao; Ofek, Eran O.; Laher, Russ; Masci, Frank; Levitan, David; et al. (September 2015). "Asteroid Light Curves from the Palomar Transient Factory Survey: Rotation Periods and Phase Functions from Sparse Photometry". The Astronomical Journal. 150 (3): 35. arXiv:1504.04041Freely accessible. Bibcode:2015AJ....150...75W. doi:10.1088/0004-6256/150/3/75. Retrieved 24 October 2017. 
  9. ^ 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 24 October 2017. 
  10. ^ a b "1393 Sofala (1936 KD)". Minor Planet Center. Retrieved 24 October 2017. 
  11. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 24 October 2017. 

External links[edit]