1928 Summa

1928 Summa, provisional designation 1938 SO, is a stony asteroid from the inner regions of the asteroid belt, approximately 9 kilometers in diameter.

1928 Summa
Discovery [1]
Discovered byY. Väisälä
Discovery siteTurku Obs.
Discovery date21 September 1938
Designations
(1928) Summa
Named after
Finnish village
(Battle of Summa)[2]
1938 SO · 1969 PA
main-belt · (inner) [3]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc78.38 yr (28,628 days)
Aphelion2.9797 AU
Perihelion1.9733 AU
2.4765 AU
Eccentricity0.2032
3.90 yr (1,423 days)
98.003°
0° 15m 10.44s / day
Inclination4.5756°
180.42°
157.80°
Physical characteristics
Dimensions8.34 km (derived)[3]
9.333±0.170 km[4][5]
6.8549±0.0006 h[6]
6.855±0.001 h[7]
9.66 h (dated)[8]
0.160±0.043[4][5]
0.20 (assumed)[3]
S [3][8]
B–V = 1.010[1]
12.68[1] · 12.76[3][4][8] · 13.20±0.85[9]

    It was discovered on 21 September 1938, by Finnish astronomer Yrjö Väisälä at Turku Observatory in Southwest Finland.[10] It was named for a Finnish village where the Battle of Summa took place.[2]

    Orbit and classification

    Summa is a S-type asteroid that orbits the Sun in the inner main-belt at a distance of 2.0–3.0 AU once every 3 years and 11 months (1,423 days). Its orbit has an eccentricity of 0.20 and an inclination of 5° with respect to the ecliptic.[1] The body's observation arc begins at Turku one night after its official discovery observation, with no precoveries taken, and no prior identifications made.[10]

    Rotation period

    In March 1984, the first but poorly rated rotational lightcurve of Summa was obtained from photometric observations by American astronomer Richard Binzel. It gave a rotation period of 9.66 hours with a brightness amplitude of 0.14 magnitude (U=1).[8]

    In August 2012, a refined yet ambiguous lightcurve with a period of 6.855 hours and an amplitude of 0.13 was obtained by Larry E. Owings at the Barnes Ridge Observatory in California (U=2+). Lightcurve analysis also considered that Summa might be a binary system.[7] One month later, the so-far best rated lightcurve from British astronomer Kevin Hills using the remote controlled Riverland Dingo Observatory in Australia, gave a period of 6.8549 hours with a brightness amplitude of 0.18 (U=3).[6]

    Diameter an albedo

    According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Summa measures 9.333 kilometers in diameter and its surface has an albedo of 0.160,[4][5] while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 8.34 kilometers with an absolute magnitude of 12.76.[3]

    Naming

    This minor planet was named after the village on the Karelian Isthmus, where the Battle of Summa took place during the Finnish Winter War (1939–1940).[2] The approved naming citation was published by the Minor Planet Center on 1 August 1980 (M.P.C. 5450).[11] Most of Yrjö Väisälä's discoveries have names that relate in one way or another to this military conflict between Finland and the Soviet Union during World War II.

    References
    1. "JPL Small-Body Database Browser: 1928 Summa (1938 SO)" (2017-02-08 last obs.). Jet Propulsion Laboratory. Retrieved 2 July 2017.
    2. Schmadel, Lutz D. (2007). "(1928) Summa". Dictionary of Minor Planet Names – (1928) Summa. Springer Berlin Heidelberg. p. 155. doi:10.1007/978-3-540-29925-7_1929. ISBN 978-3-540-00238-3.
    3. "LCDB Data for (1928) Summa". Asteroid Lightcurve Database (LCDB). Retrieved 5 April 2017.
    4. 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.
    5. Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Dailey, J.; et al. (November 2011). "Main Belt Asteroids with WISE/NEOWISE. I. Preliminary Albedos and Diameters". The Astrophysical Journal. 741 (2): 20. arXiv:1109.4096. Bibcode:2011ApJ...741...68M. doi:10.1088/0004-637X/741/2/68. Retrieved 5 April 2017.
    6. Hills, Kevin (January 2013). "Asteroid Lightcurve Analysis at Riverland Dingo Observatory (RDO): 501 Urhixidur, 1897 Hind, 1928 Summa, 6261 Chione, and (68216) 2001 CV 26". The Minor Planet Bulletin. 40 (1): 12–13. Bibcode:2013MPBu...40...12H. ISSN 1052-8091. Retrieved 5 April 2017.
    7. Owings, Larry E. (April 2013). "Lightcurves for 1560 Strattonia, 1928 Summa, 2763 Jeans, 3478 Fanale, 3948 Bohr, 5275 Zdislava, and 5369 Virgiugum". The Minor Planet Bulletin. 40 (2): 104–106. Bibcode:2013MPBu...40..104O. ISSN 1052-8091. Retrieved 5 April 2017.
    8. Binzel, R. P. (October 1987). "A photoelectric survey of 130 asteroids". Icarus. 72 (1): 135–208. Bibcode:1987Icar...72..135B. doi:10.1016/0019-1035(87)90125-4. ISSN 0019-1035. Retrieved 5 April 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:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 5 April 2017.
    10. "1928 Summa (1938 SO)". Minor Planet Center. Retrieved 5 April 2017.
    11. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 5 April 2017.

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