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1845 Helewalda

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1845 Helewalda
Discovery [1]
Discovered byP. Wild
Discovery siteZimmerwald Obs.
Discovery date30 October 1972
Designations
1845 Helewalda
Named after
Helen Gachnang
(friend of discoverer)[2]
1972 UC · 1931 VC1
1954 GG · 1971 OR
1971 QX2
main-belt · (outer) [3]
Orbital characteristics [1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc84.46 yr (30,849 days)
Aphelion3.1371 AU
Perihelion2.7992 AU
2.9682 AU
Eccentricity0.0569
5.11 yr (1,868 days)
132.95°
0° 11m 33.72s / day
Inclination10.720°
142.61°
325.22°
Physical characteristics
Dimensions20.426±0.147 km[4]
32.03 km (calculated)[3]
7.2786±0.0002 h[5]
7.399±0.004 h[6]
7.4±0.1 h[7]
7.3985±0.0098 h[8]
0.1289±0.0185[4]
0.057 (assumed)[3]
C [3]
11.193±0.002[8]
11.2[1][3]
11.3[4]
11.60±0.98[9]

1845 Helewalda, provisional designation 1972 UC, is a carbonaceous asteroid in the outer regions of the asteroid belt, approximately 25 kilometers in diameter. It was discovered by Swiss astronomer Paul Wild at Zimmerwald Observatory near Bern, Switzerland, on 30 October 1972.[10]

The C-typeasteroid orbits the Sun at a distance of 2.8–3.1 AU once every 5 years and 1 month (1,868 days). Its orbit has an eccentricity of 0.06 and an inclination of 11° with respect to the ecliptic.[1] The first precovery was taken at Lowell Observatory in 1931, extending the asteroid's observation arc by 41 years prior to its discovery.[10]

Based on observations made by French astronomer René Roy in March 2010, Helewalda has a well-determined rotation period of 7.2786±0.0002 hours with a brightness variation of 0.26 in magnitude (U=3-).[5] Between 2009 and 2015, other light-curves were obtained at the Oakley Southern Sky Observatory in Australia (E09), the Via Capote Observatory at Thousand Oaks, California (G69), and the Palomar Transient Factory at Palomar Observatory. They gave a similar period of 7.399±0.004, 7.4±0.1 and 7.3985±0.0098 hours with a corresponding amplitude of 0.20, 0.28 and 0.15, respectively (U=2/2+/2).[6][7][8]

The Collaborative Asteroid Lightcurve Link calculates a diameter of 32.0 kilometers, based on an assumed standard albedo for carbonaceous C-type asteroids of 0.057,[3] while the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer measured a higher albedo of 0.129 and a diameter of 20.4 kilometers in diameter.[4]

The discoverer, Paul Wildt, named a pair of asteroids after two of his former schoolmates, Susi and Helen, both from the small village of Wald, Zürich in Switzerland. This one was dedicated to Helen Gachnang, while the previously numbered asteroid 1844 Susilva was given to Susi Petit-Pierre.[2][11] Naming citation was published before November 1977 (M.P.C. 4156).[12]

References

  1. ^ a b c d "JPL Small-Body Database Browser: 1845 Helewalda (1972 UC)" (2016-04-20 last obs.). Jet Propulsion Laboratory. Retrieved 18 May 2016.
  2. ^ a b Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (1845) Helewalda. Springer Berlin Heidelberg. p. 148. ISBN 978-3-540-00238-3. Retrieved 18 May 2016.
  3. ^ a b c d e f "LCDB Data for (1845) Helewalda". Asteroid Lightcurve Database (LCDB). Retrieved 18 May 2016.
  4. ^ 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". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. Retrieved 18 May 2016.
  5. ^ a b Behrend, Raoul. "Asteroids and comets rotation curves – (1845) Helewalda". Geneva Observatory. Retrieved 18 May 2016.
  6. ^ a b Carbo, Landry; Green, Dawson; Kragh, Katherine; Krotz, Jonathan; Meiers, Andrew; Patino, Bernadette; et al. (October 2009). "Asteroid Lightcurve Analysis at the Oakley Southern Sky Observatory: 2008 October thru 2009 March". The Minor Planet Bulletin. 36 (4): 152–157. Bibcode:2009MPBu...36..152C. ISSN 1052-8091. Retrieved 18 May 2016.
  7. ^ a b Brinsfield, James W. (October 2010). "Asteroid Lightcurve Analysis at the Via Capote Observatory: 2010 February-May". The Minor Planet Bulletin. 37 (4): 146–147. Bibcode:2010MPBu...37..146B. ISSN 1052-8091. Retrieved 18 May 2016.
  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:1504.04041. Bibcode:2015AJ....150...75W. doi:10.1088/0004-6256/150/3/75. Retrieved 18 May 2016.
  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 18 May 2016.
  10. ^ a b "1845 Helewalda (1972 UC)". Minor Planet Center. Retrieved 18 May 2016.
  11. ^ "Himmlischer Besuch auf der Sternwarte Eschenberg" (in German). Sternwarte Eschenberg. Retrieved 1 March 2016. Helen Gachnang and Susi Petit-Pierre visit the Eschenberg Observatory
  12. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 18 May 2016.
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