994 Otthild

994 Otthild (prov. designation: A923 FB or 1923 NL) is a stony background asteroid from the central regions of the asteroid belt, approximately 24 kilometers (15 miles) in diameter. It was discovered on 18 March 1923, by astronomer Karl Reinmuth at the Heidelberg-Königstuhl State Observatory.[1] The S-type asteroid has a rotation period of 5.95 hours and is rather regular in shape. It was named after a common German female name, unrelated to the discoverer's contemporaries, and taken from the almanac Lahrer Hinkender Bote.[2][3]

994 Otthild
Lightcurve-based 3D-model of Otthild
Discovery [1]
Discovered byK. Reinmuth
Discovery siteHeidelberg Obs.
Discovery date18 March 1923
Designations
(994) Otthild
Named after
Name picked from the almanac
Lahrer Hinkender Bote [2][3]
A923 FB · 1923 NL
1960 KC · 1967 CM
1967 EK1 · 1923 NL
main-belt [1][4] · (middle)
background [5]
Orbital characteristics [4]
Epoch 27 April 2019 (JD 2458600.5)
Uncertainty parameter 0
Observation arc96.15 yr (35,119 d)
Aphelion2.8235 AU
Perihelion2.2349 AU
2.5292 AU
Eccentricity0.1164
4.02 yr (1,469 d)
156.20°
0° 14m 42s / day
Inclination15.411°
2.3500°
342.50°
Physical characteristics
Mean diameter
  • 20.786±1.371 km[6]
  • 24.34±0.61 km[7]
  • 24.42±1.6 km[8]
5.9473±0.0001 h[9][lower-alpha 1]
  • (183.0°, −50.0°) (λ1/β1)[10]
  • (41.0°, −39.0°) (λ2/β2)[10]
  • 0.2247±0.032[8]
  • 0.227±0.013[7]
  • 0.310±0.036[6]
10.2[1][4]

    Orbit and classification

    Otthild is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements.[5] It orbits the Sun in the central asteroid belt at a distance of 2.2–2.8 AU once every 4 years (1,469 days; semi-major axis of 2.53 AU). Its orbit has an eccentricity of 0.12 and an inclination of 15° with respect to the ecliptic.[4] The body's observation arc begins on 20 March 1931 at Heidelberg just two days after its official discovery observation.[1]

    Naming

    This minor planet was named Otthild, after a female name picked from the Lahrer Hinkender Bote, published in Lahr, southern Germany.[2][3] A Hinkender Bote (lit. "limping messenger") was a very popular almanac, especially in the alemannic-speaking region from the late 17th throughout the early 20th century. The calendar section contains feast days, the dates of important fairs and astronomical ephemerides. For the second of July, the calendar gives "Otto" and "Otthild" as the German analogue for the catholic and protestant feast-days (Mary's Visitation and Otto).[11]

    Reinmuth's calendar names

    As with 913 Otila, 997 Priska and 1144 Oda, Reinmuth selected names from this calendar due to his many asteroid discoveries that he had trouble thinking of proper names. These names are not related to the discoverer's contemporaries. The author of the Dictionary of Minor Planet Names learned about Reinmuth's source of inspiration from private communications with Dutch astronomer Ingrid van Houten-Groeneveld, who worked as a young astronomer at Heidelberg.[2]

    Physical characteristics

    In the Bus–Binzel SMASS classification, Otthild is a common, stony S-type asteroid.[4][10]

    Rotation period

    In October 2005, a rotational lightcurve of Otthild was obtained from photometric observations by European observers Reiner Stoss, Jaume Nomen, Salvador Sanchez, Raoul Behrend and Laurent Bernasconi. Lightcurve analysis gave a rotation period of 5.9473±0.0001 hours with a relatively low brightness amplitude of 0.15±0.01 magnitude (U=2+), which is indicative of a regular shape.[9][12][lower-alpha 1]

    Poles

    A modeled lightcurve gave a concurring sidereal period of 5.94819 hours using data from the Uppsala Asteroid Photometric Catalogue, the Palomar Transient Factory survey, and individual observers (such as above), as well as sparse-in-time photometry from the NOFS, the Catalina Sky Survey, and the La Palma surveys (950). The study also determined two spin axes of (183.0°, −50.0°) and (41.0°, −39.0°) in ecliptic coordinates (λ, β).[13]

    Diameter and albedo

    According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Otthild measures (20.786±1.371) kilometers in diameter and its surface has an albedo of (0.310±0.036).[6] The Japanese Akari satellite and the Infrared Astronomical Satellite IRAS determined a somewhat larger diameter of (24.34±0.61) and (24.42±1.6) kilometers with an albedo of (0.227±0.013) and (0.2247±0.032), respectively.[7][8] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.2136 and a diameter of 24.36 kilometers based on an absolute magnitude of 10.36.[12]

    Notes
    1. Lightcurve plot (994) Otthild produced by Reiner Stoss and Laurent Bernasconi. The obtained rotation period was 0.247804 days (5.9473 hours). Summary figures at Raoul Behrend – Geneva Observatory.

    References
    1. "994 Otthild (A923 FB)". Minor Planet Center. Retrieved 22 January 2020.
    2. Schmadel, Lutz D. (2007). "(994) Otthild". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 86. doi:10.1007/978-3-540-29925-7_995. ISBN 978-3-540-00238-3.
    3. "Lahrer hinkender Bote – Kalender 1925". Baden State Library. 1925. p. 1. Retrieved 22 January 2020. Lahrer Bote collection
    4. "JPL Small-Body Database Browser: 994 Otthild (A923 FB)" (2019-05-12 last obs.). Jet Propulsion Laboratory. Retrieved 22 January 2020.
    5. "Asteroid 994 Otthild – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 22 January 2020.
    6. 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:1209.5794. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8.
    7. Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. (online, AcuA catalog p. 153)
    8. Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System. 12: IRAS-A-FPA-3-RDR-IMPS-V6.0. Bibcode:2004PDSS...12.....T. Retrieved 22 January 2020.
    9. Behrend, Raoul. "Asteroids and comets rotation curves – (994) Otthild". Geneva Observatory. Retrieved 22 January 2020.
    10. "Asteroid 994 Otthild". Small Bodies Data Ferret. Retrieved 22 January 2020.
    11. "Lahrer hinkender Bote – Kalender 1925". Baden State Library. 1925. p. 14. Retrieved 20 February 2020.
    12. "LCDB Data for (994) Otthild". Asteroid Lightcurve Database (LCDB). Retrieved 22 January 2020.
    13. Hanuš, J.; Ďurech, J.; Brož, 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". Astronomy and Astrophysics. 551: 16. arXiv:1301.6943. Bibcode:2013A&A...551A..67H. doi:10.1051/0004-6361/201220701.
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