1946 Walraven

1946 Walraven (prov. designation: 1931 PH) is a stony asteroid from the inner regions of the asteroid belt, approximately 10 kilometers in diameter. It was discovered on 8 August 1931, by Dutch astronomer Hendrik van Gent at Leiden Southern Station, annex to the Johannesburg Observatory in South Africa, and named after astronomer Theodore Walraven.[2][10]

1946 Walraven
Modelled shape of Walraven from its lightcurve
Discovery [1]
Discovered byH. van Gent
Discovery siteJohannesburg Obs.
(Leiden Southern Station)
Discovery date8 August 1931
Designations
(1946) Walraven
Named after
Theodore Walraven
(astronomer)[2]
1931 PH · 1952 PB
1959 RE1 · 1966 TC
1972 JE1
main-belt · (inner) [3]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc85.73 yr (31,314 days)
Aphelion2.8329 AU
Perihelion1.7564 AU
2.2947 AU
Eccentricity0.2346
3.48 yr (1,270 days)
242.32°
0° 17m 0.6s / day
Inclination8.1606°
17.269°
340.01°
Physical characteristics
Mean diameter
9.205±0.109 km[4][5]
11.83 km (calculated)[3]
10.21±0.01 h[6]
10.2101±0.0005 h[7]
10.22±0.02 h[8]
10.223 h[9]
0.20 (assumed)[3]
0.362±0.067[4][5]
S [3]
11.9[4] · 12.0[1][3]

    Classification and orbit

    Walraven is a stony S-type asteroid that orbits the Sun in the inner main-belt at a distance of 1.8–2.8 AU once every 3 years and 6 months (1,270 days). Its orbit has an eccentricity of 0.23 and an inclination of 8° with respect to the ecliptic.[1] The body's observation arc begins one day prior to its official discovery observation.[10]

    Naming

    This minor planet was named in honor of astronomer and pioneer in optical instrumentation and precision photometry, Theodore Fjeda Walraven (1916–2008),[11] who was a professor at the Leiden University and for many years resident astronomer at the former Leiden Southern Station near Hartbeespoortdam, South Africa.

    Walraven constructed special photometers for the telescopes at the station, including the 5-color photometer for which he developed the Walraven photometric system.[2] The approved naming citation was published by the Minor Planet Center on 2 April 1988 (M.P.C. 12968).[12]

    Physical characteristics

    Rotation period

    Four rotational lightcurves of Walraven were obtained from photometric observation, giving a rotation period between 10.210 and 10.223 hours with a brightness variation of 0.60 to 0.90 magnitude (U=2+/n.a./2/2).[6][7][8][9]

    Diameter and albedo

    According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Walraven measures 9.2 kilometers in diameter and its surface has an albedo of 0.362,[4][5] while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20, and calculates a diameter of 11.8 kilometers with an absolute magnitude of 12.0.[3]

    References
    1. "JPL Small-Body Database Browser: 1946 Walraven (1931 PH)" (2017-05-01 last obs.). Jet Propulsion Laboratory. Retrieved 2 July 2017.
    2. Schmadel, Lutz D. (2007). "(1946) Walraven". Dictionary of Minor Planet Names – (1946) Walraven. Springer Berlin Heidelberg. p. 156. doi:10.1007/978-3-540-29925-7_1947. ISBN 978-3-540-00238-3.
    3. "LCDB Data for (1946) Walraven". Asteroid Lightcurve Database (LCDB). Retrieved 9 December 2016.
    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 9 December 2016.
    6. Aznar Macias, Amadeo; Carreno Garcerain, Alfonso; Arce Masego, Enrique; Brines Rodriguez, Pedro; Lozano de Haro, Juan; Fornas Silva, Alvaro; et al. (July 2016). "Twenty-one Asteroid Lightcurves at Group Observadores de Asteroides (OBAS): Late 2015 to Early 2016". The Minor Planet Bulletin. 43 (3): 257–263. Bibcode:2016MPBu...43..257A. ISSN 1052-8091. Retrieved 9 December 2016.
    7. Hanus, J.; Durech, J.; Oszkiewicz, D. A.; Behrend, R.; Carry, B.; Delbo, M.; et al. (February 2016). "New and updated convex shape models of asteroids based on optical data from a large collaboration network". Astronomy and Astrophysics. 586: 24. arXiv:1510.07422. Bibcode:2016A&A...586A.108H. doi:10.1051/0004-6361/201527441. Retrieved 9 December 2016.
    8. Folberth, James; Casimir, Serick; Dou, Yueheng; Evans, Davis; Foulkes, Thomas; Haenftling, Miranda; et al. (April 2012). "Asteroid Lightcurve Analysis at the Oakley Southern Sky Observatory: 2011 July-September". The Minor Planet Bulletin. 39 (2): 51–55. Bibcode:2012MPBu...39...51F. ISSN 1052-8091. Retrieved 9 December 2016.
    9. van Gent, H. (May 1933). "Period, light-curve, and ephemeris of the new asteroid with variable brightness 1931 PH". Bulletin of the Astronomical Institutes of the Netherlands. 7: 65. Bibcode:1933BAN.....7...65V. Retrieved 9 December 2016.
    10. "1946 Walraven (1931 PH)". Minor Planet Center. Retrieved 9 December 2016.
    11. "Theodore Walraven (1916–2008) Dutch pioneer in optical instrumentation and precision photometry". Leiden Observatory. Archived from the original on 24 September 2015. Retrieved 7 November 2015.
    12. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 9 December 2016.

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