1845 Helewalda

Carbonaceous Eoan asteroid October 2019 yes 1845 Helewalda #D6D6D6 30 October 1972 P. Wild Zimmerwald Obs. (1845) Helewalda 1972 UC1931 VC 11954 GG1971 OR1971 QX 2 Helen Gachnang(friend of discoverer) main-belt(outer)Eos 4 September 2017 (JD 2458000.5) 0 85.50 yr (31,229 days) 3.1371 AU 2.8001 AU 2.9686 AU 0.0568 5.11 yr (1,868 days) 210.23° 0.1927 ms / day 10.720° 142.61° 325.05° 19.930 0.37720.426 0.147 km32.03 km (calculated) 7.2786 0.0002 h7.3985 0.0098 h7.399 0.004 h7.4 0.1 h 0.057 (assumed)0.1289 0.01850.134 0.014 C (assumed) 11.193 0.00211.211.311.60 0.98 1845 Helewalda (provisional designation 1972 UC) is a carbonaceous Eoan asteroid in the outer regions of the asteroid belt, approximately 20 kilometers in diameter. It was discovered by Swiss astronomer Paul Wild at Zimmerwald Observatory near Bern, Switzerland, on 30 October 1972. The asteroid was named after Helen Gachnang, a friend of the discoverer. Orbit and classification Helewalda is a member of the Eos family (606), the largest asteroid family in the outer main belt consisting of nearly 10,000 asteroids.23 It orbits the Sun in the outer main-belt 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. The first precovery was taken at Lowell Observatory in 1931, extending the asteroid's observation arc by 41 years prior to its discovery. Physical characteristics Helewalda is an assumed carbonaceous C-type asteroid. Rotation period 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-). Between 2009 and 2015, other lightcurves 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). Diameter and albedo 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, while the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer measured a higher albedo of 0.134 and 0.129 and a corresponding diameter of 19.9 and 20.4 kilometers in diameter, respectively. Naming The discoverer, Paul Wild, 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. The official 1845 naming citation was published by the Minor Planet Center on 18 April 1977 (M.P.C. 4156). References 30em 2017-05-05 last obs. JPL Small-Body Database Browser: 1845 Helewalda (1972 UC) https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2001845 Jet Propulsion Laboratory 8 June 2017 Schmadel Lutz D. Dictionary of Minor Planet Names Springer Berlin Heidelberg 148 2007 978-3-540-00238-3 10.1007/978-3-540-29925-7_1846 (1845) Helewalda 1845 Helewalda (1972 UC) Minor Planet Center https://www.minorplanetcenter.net/db_search/show_object?object_id=1845 18 May 2016 Dictionary of Minor Planet Names – Addendum to Fifth Edition (2006–2008) 2009 https://archive.org/details/dictionaryminorp2008schm limited Appendix – Publication Dates of the MPCs Schmadel Lutz D. Springer Berlin Heidelberg 221 978-3-642-01964-7 10.1007/978-3-642-01965-4 Asteroids and comets rotation curves – (1845) Helewalda Behrend Raoul Geneva Observatory http://obswww.unige.ch/~behrend/page4cou.html#001845 18 May 2016 1 April 2019 https://web.archive.org/web/20190401181659/http://obswww.unige.ch/~behrend/page4cou.html#001845 dead Asteroid 1845 Helewalda – Nesvorny HCM Asteroid Families V3.0 Small Bodies Data Ferret https://sbntools.psi.edu/ferret/SimpleSearch/results.action?targetName=1845+Helewalda#Asteroid%201845%20HelewaldaEAR-A-VARGBDET-5-NESVORNYFAM-V3.0 26 October 2019 https://web.archive.org/web/20201108052157/https://sbntools.psi.edu/ferret/SimpleSearch/results.action?targetName=1845+Helewalda#Asteroid%201845%20HelewaldaEAR-A-VARGBDET-5-NESVORNYFAM-V3.0 8 November 2020 dead D. Nesvorný M. Broz V. Carruba December 2014 Identification and Dynamical Properties of Asteroid Families Asteroids IV 297–321 2015aste.book..297N 10.2458/azu_uapress_9780816532131-ch016 1502.01628 9780816532131 1845 18 May 2016 Himmlischer Besuch auf der Sternwarte Eschenberg Helen Gachnang and Susi Petit-Pierre visit the Eschenberg Observatory German Sternwarte Eschenberg http://www.eschenberg.ch/sternwarte.php?sec=hd 1 March 2016 6 A. Mainzer T. Grav J. Masiero E. Hand J. Bauer D. Tholen R. S. McMillan T. Spahr R. M. Cutri E. Wright J. Watkins W. Mo C. Maleszewski November 2011 NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2011ApJ...741...90M The Astrophysical Journal 741 2 25 2011ApJ...741...90M 10.1088/0004-637X/741/2/90 1109.6407 18 May 2016 6 Landry Carbo Dawson Green Katherine Kragh Jonathan Krotz Andrew Meiers Bernadette Patino Zachary Pligge Nelson Shaffer Richard Ditteon October 2009 Asteroid Lightcurve Analysis at the Oakley Southern Sky Observatory: 2008 October thru 2009 March http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2009MPBu...36..152C The Minor Planet Bulletin 36 4 152–157 1052-8091 2009MPBu...36..152C 18 May 2016 Brinsfield, James W. October 2010 Asteroid Lightcurve Analysis at the Via Capote Observatory: 2010 February–May http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2010MPBu...37..146B The Minor Planet Bulletin 37 4 146–147 1052-8091 2010MPBu...37..146B 18 May 2016 6 Adam Waszczak Chan-Kao Chang Eran O. Ofek Russ Laher Frank Masci David Levitan Jason Surace Yu-Chi Cheng Wing-Huen Ip Daisuke Kinoshita George Helou Thomas A. Prince Shrinivas Kulkarni September 2015 Asteroid Light Curves from the Palomar Transient Factory Survey: Rotation Periods and Phase Functions from Sparse Photometry http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2015AJ....150...75W The Astronomical Journal 150 3 35 2015AJ....150...75W 10.1088/0004-6256/150/3/75 1504.04041 18 May 2016 6 Peter Veres Robert Jedicke Alan Fitzsimmons Larry Denneau Mikael Granvik Bryce Bolin Serge Chastel Richard J. Wainscoat William S. Burgett Kenneth C. Chambers Heather Flewelling Nick Kaiser Eugen A. Magnier Jeff S. Morgan Paul A. Price John L. Tonry Christopher Waters November 2015 Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2015Icar..261...34V Icarus 261 34–47 2015Icar..261...34V 10.1016/j.icarus.2015.08.007 1506.00762 18 May 2016 6 Joseph R. Masiero T. Grav A. K. Mainzer C. R. Nugent J. M. Bauer R. Stevenson S. Sonnett August 2014 Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2014ApJ...791..121M The Astrophysical Journal 791 2 11 2014ApJ...791..121M 10.1088/0004-637X/791/2/121 1406.6645 8 December 2016 External links Asteroid Lightcurve Database (LCDB), query form (info https://web.archive.org/web/20171216050541/http://www.minorplanet.info/lightcurvedatabase.html 16 December 2017 ) Dictionary of Minor Planet Names, Google books Asteroids and comets rotation curves, CdR https://web.archive.org/web/20160729213840/http://obswww.unige.ch/~behrend/page_cou.html 29 July 2016 – Observatoire de Genève, Raoul Behrend Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center 1845 1844 Susilva 1845 1846 Bengt 001845 Category:Discoveries by Paul Wild (Swiss astronomer) Category:Named minor planets 19721030