1845 Helewalda

1845 Helewalda
Discovery [1]
Discovered by P. Wild
Discovery site Zimmerwald Obs.
Discovery date 30 October 1972
Designations
MPC designation 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 13 January 2016 (JD 2457400.5)
Uncertainty parameter 0
Observation arc 84.29 yr (30,787 days)   
Aphelion 3.1378 AU
Perihelion 2.7998 AU
2.9688 AU
Eccentricity 0.0569
5.12 yr (1,868 days)
94.138°
Inclination 10.720°
142.61°
325.47°
Physical characteristics
Dimensions 20.426±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]
11.2[1][3]
11.3[4]
11.193±0.002[8]
11.60±0.98[9]

    1845 Helewalda, provisional designation 1972 UC, is a carbonaceous asteroid in the outer regions of the asteroid belt. It orbits the Sun at a distance of 2.8–3.1 AU once every 5.12 years (1,870 days).[3] The asteroid was discovered by Swiss astronomer Paul Wild at Zimmerwald Observatory near Bern, Switzerland, on 30 October 1972.[10]

    Helewalda has a well-determined rotation period of 7.3 hours with an amplitude in brightness of 0.26 in magnitude (U=3-).[5] Several other photometric light-curve measurements taken or evaluated between 2009 and 2015, also rendered a period between 7.3 and 7.4 hours.[6][7][8]

    The Collaborative Asteroid Lightcurve Link (CALL) calculated the body's diameter to be about 32 kilometers, based on an assumed albedo of 0.057 for a C-type asteroid, while measurements from NASA's NEOWISE mission detected it to be much more reflective and therefore only 20 kilometers in diameter.[3][4]

    The discoverer 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]

    References

    1. 1 2 3 "JPL Small-Body Database Browser: 1845 Helewalda (1972 UC)" (2016-02-18 last obs.). Jet Propulsion Laboratory. Retrieved March 2016.
    2. 1 2 Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (1845) Helewalda. Springer Berlin Heidelberg. p. 148. ISBN 978-3-540-00238-3. Retrieved March 2016.
    3. 1 2 3 4 5 6 7 "LCDB Data for (1845) Helewalda". Asteroid Lightcurve Database (LCDB). Retrieved March 2016.
    4. 1 2 3 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. Retrieved November 2015.
    5. 1 2 Roy, René. "Asteroids and comets rotation curves (1845) Helewalda". Geneva Observatory – Raoul Behrend. Retrieved November 2015.
    6. 1 2 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 November 2015.
    7. 1 2 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 November 2015.
    8. 1 2 3 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 November 2015.
    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 March 2016.
    10. ↑ "1845 Helewalda (1972 UC)". Minor Planet Center. Retrieved March 2016.
    11. ↑ "Himmlischer Besuch auf der Sternwarte Eschenberg" (in German). Sternwarte Eschenberg. Retrieved March 2016. Helen Gachnang and Susi Petit-Pierre visit the Eschenberg Observatory

    External links


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